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fcb74331c483cdade3007fbe7bfbc60d152841c8
542 Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
 Qing Wang
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91f3e8d84c |
tracing: Fix WARN_ON in tracing_buffers_mmap_close
commit |
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 Masami Hiramatsu (Google)
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b4700c089a |
tracing: ring-buffer: Fix to check event length before using
[ Upstream commit |
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 Wupeng Ma
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4cd8f97999 |
ring-buffer: Avoid softlockup in ring_buffer_resize() during memory free
[ Upstream commit |
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 Steven Rostedt
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b42dbef4f2 |
ring-buffer: Do not warn in ring_buffer_map_get_reader() when reader catches up
commit |
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Steven Rostedt
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5763daf5ca |
ring-buffer: Remove ring_buffer_read_prepare_sync()
[ Upstream commit |
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Steven Rostedt
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2d6a6cfe96 |
ring-buffer: Move cpus_read_lock() outside of buffer->mutex
commit |
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 Dmitry Antipov
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e09c0600be |
ring-buffer: Fix buffer locking in ring_buffer_subbuf_order_set()
commit |
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Steven Rostedt
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b8df8cb8f7 |
ring-buffer: Do not trigger WARN_ON() due to a commit_overrun
commit |
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Steven Rostedt
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20d6e621be |
ring-buffer: Fix persistent buffer when commit page is the reader page
commit |
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Steven Rostedt
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92ca7270fe |
ring-buffer: Use flush_kernel_vmap_range() over flush_dcache_folio()
commit |
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 Feng Yang
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2a6f8823ff |
ring-buffer: Fix bytes_dropped calculation issue
[ Upstream commit |
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Steven Rostedt
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9f837ea922 |
ring-buffer: Update pages_touched to reflect persistent buffer content
commit |
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Steven Rostedt
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3ec743d558 |
ring-buffer: Validate the persistent meta data subbuf array
commit |
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Steven Rostedt
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abb99f28b4 |
ring-buffer: Unlock resize on mmap error
commit |
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Steven Rostedt
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ed0ad04c68 |
ring-buffer: Do not allow events in NMI with generic atomic64 cmpxchg()
commit |
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 Jeongjun Park
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22a1a75818 |
ring-buffer: Make reading page consistent with the code logic
[ Upstream commit
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 Edward Adam Davis
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ec12f30fe5 |
ring-buffer: Fix overflow in __rb_map_vma
commit |
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 Petr Pavlu
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09c083fbea |
ring-buffer: Limit time with disabled interrupts in rb_check_pages()
[ Upstream commit
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Steven Rostedt
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580bb355bc |
Revert: "ring-buffer: Do not have boot mapped buffers hook to CPU hotplug"
A crash happened when testing cpu hotplug with respect to the memory mapped ring buffers. It was assumed that the hot plug code was adding a per CPU buffer that was already created that caused the crash. The real problem was due to ref counting and was fixed by commit |
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Petr Pavlu
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09661f75e7 |
ring-buffer: Fix reader locking when changing the sub buffer order
The function ring_buffer_subbuf_order_set() updates each
ring_buffer_per_cpu and installs new sub buffers that match the requested
page order. This operation may be invoked concurrently with readers that
rely on some of the modified data, such as the head bit (RB_PAGE_HEAD), or
the ring_buffer_per_cpu.pages and reader_page pointers. However, no
exclusive access is acquired by ring_buffer_subbuf_order_set(). Modifying
the mentioned data while a reader also operates on them can then result in
incorrect memory access and various crashes.
Fix the problem by taking the reader_lock when updating a specific
ring_buffer_per_cpu in ring_buffer_subbuf_order_set().
Link: https://lore.kernel.org/linux-trace-kernel/20240715145141.5528-1-petr.pavlu@suse.com/
Link: https://lore.kernel.org/linux-trace-kernel/20241010195849.2f77cc3f@gandalf.local.home/
Link: https://lore.kernel.org/linux-trace-kernel/20241011112850.17212b25@gandalf.local.home/
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/20241015112440.26987-1-petr.pavlu@suse.com
Fixes:
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Steven Rostedt
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912da2c384 |
ring-buffer: Do not have boot mapped buffers hook to CPU hotplug
The boot mapped ring buffer has its buffer mapped at a fixed location
found at boot up. It is not dynamic. It cannot grow or be expanded when
new CPUs come online.
Do not hook fixed memory mapped ring buffers to the CPU hotplug callback,
otherwise it can cause a crash when it tries to add the buffer to the
memory that is already fully occupied.
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/20241008143242.25e20801@gandalf.local.home
Fixes:
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 Vincent Donnefort
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eb2dcde9f9 |
ring-buffer: Align meta-page to sub-buffers for improved TLB usage
Previously, the mapped ring-buffer layout caused misalignment between the meta-page and sub-buffers when the sub-buffer size was not a multiple of PAGE_SIZE. This prevented hardware with larger TLB entries from utilizing them effectively. Add a padding with the zero-page between the meta-page and sub-buffers. Also update the ring-buffer map_test to verify that padding. Link: https://lore.kernel.org/20240628104611.1443542-1-vdonnefort@google.com Signed-off-by: Vincent Donnefort <vdonnefort@google.com> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> |
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Steven Rostedt
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d0f2d6e951 |
ring-buffer: Add magic and struct size to boot up meta data
Add a magic number as well as save the struct size of the ring_buffer_meta structure in the meta data to also use as validation. Updating the magic number could be used to force a invalidation between kernel versions, and saving the structure size is also a good method to make sure the content is what is expected. Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Vincent Donnefort <vdonnefort@google.com> Link: https://lore.kernel.org/20240815115032.0c197b32@rorschach.local.home Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> |
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Steven Rostedt
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bca704f62d |
ring-buffer: Don't reset persistent ring-buffer meta saved addresses
The text and data address is saved in the meta data so that it can be used
to know the delta of the text and data addresses of the last boot compared
to the text and data addresses of the current boot. The delta is used to
convert function pointer entries in the ring buffer to something that can
be used by kallsyms (note this only works for built-in functions).
But the saved addresses get reset on boot up. If the buffer is not used
and there's another reboot, then the saved text and data addresses will be
of the last boot and not that of the boot that created the content in the
ring buffer.
To get an idea of the issue:
# trace-cmd start -B boot_mapped -p function
# reboot
# trace-cmd show -B boot_mapped | tail
<...>-1 [000] d..1. 461.983243: native_apic_msr_write <-native_kick_ap
<...>-1 [000] d..1. 461.983244: __pfx_native_apic_msr_eoi <-native_kick_ap
<...>-1 [000] d..1. 461.983244: reserve_irq_vector_locked <-native_kick_ap
<...>-1 [000] d..1. 461.983262: branch_emulate_op <-native_kick_ap
<...>-1 [000] d..1. 461.983262: __ia32_sys_ia32_pread64 <-native_kick_ap
<...>-1 [000] d..1. 461.983263: native_kick_ap <-__smpboot_create_thread
<...>-1 [000] d..1. 461.983263: store_cache_disable <-native_kick_ap
<...>-1 [000] d..1. 461.983279: acpi_power_off_prepare <-native_kick_ap
<...>-1 [000] d..1. 461.983280: __pfx_acpi_ns_delete_node <-acpi_suspend_enter
<...>-1 [000] d..1. 461.983280: __pfx_acpi_os_release_lock <-acpi_suspend_enter
# reboot
# trace-cmd show -B boot_mapped |tail
<...>-1 [000] d..1. 461.983243: 0xffffffffa9669220 <-0xffffffffa965f3db
<...>-1 [000] d..1. 461.983244: 0xffffffffa96690f0 <-0xffffffffa965f3db
<...>-1 [000] d..1. 461.983244: 0xffffffffa9663fa0 <-0xffffffffa965f3db
<...>-1 [000] d..1. 461.983262: 0xffffffffa9672e80 <-0xffffffffa965f3e0
<...>-1 [000] d..1. 461.983262: 0xffffffffa962b940 <-0xffffffffa965f3ec
<...>-1 [000] d..1. 461.983263: 0xffffffffa965f540 <-0xffffffffa96e1362
<...>-1 [000] d..1. 461.983263: 0xffffffffa963c940 <-0xffffffffa965f55b
<...>-1 [000] d..1. 461.983279: 0xffffffffa9ee30c0 <-0xffffffffa965f59b
<...>-1 [000] d..1. 461.983280: 0xffffffffa9f16c10 <-0xffffffffa9ee3157
<...>-1 [000] d..1. 461.983280: 0xffffffffa9ee02e0 <-0xffffffffa9ee3157
By not updating the saved text and data addresses in the meta data at
every boot up and only updating them when the buffer is reset, it
allows multiple boots to see the same data.
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Vincent Donnefort <vdonnefort@google.com>
Link: https://lore.kernel.org/20240815113629.0dc90af8@rorschach.local.home
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
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Steven Rostedt
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ee057c8c19 |
Merge tag 'v6.11-rc3' into trace/ring-buffer/core
The "reserve_mem" kernel command line parameter has been pulled into v6.11. Merge the latest -rc3 to allow the persistent ring buffer memory to be able to be mapped at the address specified by the "reserve_mem" command line parameter. Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> |
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 Jianhui Zhou
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58f7e4d7ba |
ring-buffer: Remove unused function ring_buffer_nr_pages()
Because ring_buffer_nr_pages() is not an inline function and user accesses buffer->buffers[cpu]->nr_pages directly, the function ring_buffer_nr_pages is removed. Signed-off-by: Jianhui Zhou <912460177@qq.com> Link: https://lore.kernel.org/tencent_F4A7E9AB337F44E0F4B858D07D19EF460708@qq.com Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> |
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 Thorsten Blum
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b96c312551 |
ring-buffer: Use vma_pages() helper function
Use the vma_pages() helper function and fix the following Coccinelle/coccicheck warning reported by vma_pages.cocci: WARNING: Consider using vma_pages helper on vma Rename the local variable vma_pages accordingly. Signed-off-by: Thorsten Blum <thorsten.blum@toblux.com> Link: https://lore.kernel.org/20240709215657.322071-2-thorsten.blum@toblux.com Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> |
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Steven Rostedt (Google)
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7a1d1e4b96 |
tracing/ring-buffer: Add last_boot_info file to boot instance
If an instance is mapped to memory on boot up, create a new file called "last_boot_info" that will hold information that can be used to properly parse the raw data in the ring buffer. It will export the delta of the addresses for text and data from what it was from the last boot. It does not expose actually addresses (unless you knew what the actual address was from the last boot). The output will look like: # cat last_boot_info text delta: -268435456 data delta: -268435456 The text and data are kept separate in case they are ever made different. Link: https://lkml.kernel.org/r/20240612232026.658680738@goodmis.org Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Vincent Donnefort <vdonnefort@google.com> Cc: Joel Fernandes <joel@joelfernandes.org> Cc: Daniel Bristot de Oliveira <bristot@redhat.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vineeth Pillai <vineeth@bitbyteword.org> Cc: Youssef Esmat <youssefesmat@google.com> Cc: Beau Belgrave <beaub@linux.microsoft.com> Cc: Alexander Graf <graf@amazon.com> Cc: Baoquan He <bhe@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: "Paul E. McKenney" <paulmck@kernel.org> Cc: David Howells <dhowells@redhat.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Guenter Roeck <linux@roeck-us.net> Cc: Ross Zwisler <zwisler@google.com> Cc: Kees Cook <keescook@chromium.org> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> |
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Steven Rostedt (Google)
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8f3e665965 |
ring-buffer: Save text and data locations in mapped meta data
When a ring buffer is mapped to a specific address, save the address of a text function and some data. This will be used to determine the delta between the last boot and the current boot for pointers to functions as well as to data. Link: https://lkml.kernel.org/r/20240612232026.496176678@goodmis.org Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Vincent Donnefort <vdonnefort@google.com> Cc: Joel Fernandes <joel@joelfernandes.org> Cc: Daniel Bristot de Oliveira <bristot@redhat.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vineeth Pillai <vineeth@bitbyteword.org> Cc: Youssef Esmat <youssefesmat@google.com> Cc: Beau Belgrave <beaub@linux.microsoft.com> Cc: Alexander Graf <graf@amazon.com> Cc: Baoquan He <bhe@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: "Paul E. McKenney" <paulmck@kernel.org> Cc: David Howells <dhowells@redhat.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Guenter Roeck <linux@roeck-us.net> Cc: Ross Zwisler <zwisler@google.com> Cc: Kees Cook <keescook@chromium.org> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> |
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Steven Rostedt (Google)
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5f3b6e839f |
ring-buffer: Validate boot range memory events
Make sure all the events in each of the sub-buffers that were mapped in a memory region are valid. This moves the code that walks the buffers for time-stamp validation out of the CONFIG_RING_BUFFER_VALIDATE_TIME_DELTAS ifdef block and is used to validate the content. Only the ring buffer event meta data and time stamps are checked and not the data load. This also has a second purpose. The buffer_page structure that points to the data sub-buffers has accounting that keeps track of the number of events that are on the sub-buffer. This updates that counter as well. That counter is used in reading the buffer and knowing if the ring buffer is empty or not. Link: https://lkml.kernel.org/r/20240612232026.172503570@goodmis.org Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Vincent Donnefort <vdonnefort@google.com> Cc: Joel Fernandes <joel@joelfernandes.org> Cc: Daniel Bristot de Oliveira <bristot@redhat.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vineeth Pillai <vineeth@bitbyteword.org> Cc: Youssef Esmat <youssefesmat@google.com> Cc: Beau Belgrave <beaub@linux.microsoft.com> Cc: Alexander Graf <graf@amazon.com> Cc: Baoquan He <bhe@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: "Paul E. McKenney" <paulmck@kernel.org> Cc: David Howells <dhowells@redhat.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Guenter Roeck <linux@roeck-us.net> Cc: Ross Zwisler <zwisler@google.com> Cc: Kees Cook <keescook@chromium.org> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> |
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Steven Rostedt (Google)
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c76883f18e |
ring-buffer: Add test if range of boot buffer is valid
Add a test against the ring buffer memory range to see if it has valid data. The ring_buffer_meta structure is given a new field called "first_buffer" which holds the address of the first sub-buffer. This is used to both determine if the other fields are valid as well as finding the offset between the old addresses of the sub-buffer from the previous boot to the new addresses of the current boot. Since the values for nr_subbufs and subbuf_size is to be the same, check if the values in the meta page match the values calculated. Take the range of the first_buffer and the total size of all the buffers and make sure the saved head_buffer and commit_buffer fall in the range. Iterate through all the sub-buffers to make sure that the values in the sub-buffer "commit" field (the field that holds the amount of data on the sub-buffer) is within the end of the sub-buffer. Also check the index array to make sure that all the indexes are within nr_subbufs. Link: https://lkml.kernel.org/r/20240612232026.013843655@goodmis.org Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Vincent Donnefort <vdonnefort@google.com> Cc: Joel Fernandes <joel@joelfernandes.org> Cc: Daniel Bristot de Oliveira <bristot@redhat.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vineeth Pillai <vineeth@bitbyteword.org> Cc: Youssef Esmat <youssefesmat@google.com> Cc: Beau Belgrave <beaub@linux.microsoft.com> Cc: Alexander Graf <graf@amazon.com> Cc: Baoquan He <bhe@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: "Paul E. McKenney" <paulmck@kernel.org> Cc: David Howells <dhowells@redhat.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Guenter Roeck <linux@roeck-us.net> Cc: Ross Zwisler <zwisler@google.com> Cc: Kees Cook <keescook@chromium.org> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> |
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Steven Rostedt (Google)
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950032ffce |
ring-buffer: Add output of ring buffer meta page
Add a buffer_meta per-cpu file for the trace instance that is mapped to boot memory. This shows the current meta-data and can be used by user space tools to record off the current mappings to help reconstruct the ring buffer after a reboot. It does not expose any virtual addresses, just indexes into the sub-buffer pages. Link: https://lkml.kernel.org/r/20240612232025.854471446@goodmis.org Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Vincent Donnefort <vdonnefort@google.com> Cc: Joel Fernandes <joel@joelfernandes.org> Cc: Daniel Bristot de Oliveira <bristot@redhat.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vineeth Pillai <vineeth@bitbyteword.org> Cc: Youssef Esmat <youssefesmat@google.com> Cc: Beau Belgrave <beaub@linux.microsoft.com> Cc: Alexander Graf <graf@amazon.com> Cc: Baoquan He <bhe@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: "Paul E. McKenney" <paulmck@kernel.org> Cc: David Howells <dhowells@redhat.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Guenter Roeck <linux@roeck-us.net> Cc: Ross Zwisler <zwisler@google.com> Cc: Kees Cook <keescook@chromium.org> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> |
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Steven Rostedt (Google)
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b14d032973 |
ring-buffer: Add ring_buffer_meta data
Populate the ring_buffer_meta array. It holds the pointer to the head_buffer (next to read), the commit_buffer (next to write) the size of the sub-buffers, number of sub-buffers and an array that keeps track of the order of the sub-buffers. This information will be stored in the persistent memory to help on reboot to reconstruct the ring buffer. Link: https://lkml.kernel.org/r/20240612232025.530733577@goodmis.org Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Vincent Donnefort <vdonnefort@google.com> Cc: Joel Fernandes <joel@joelfernandes.org> Cc: Daniel Bristot de Oliveira <bristot@redhat.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vineeth Pillai <vineeth@bitbyteword.org> Cc: Youssef Esmat <youssefesmat@google.com> Cc: Beau Belgrave <beaub@linux.microsoft.com> Cc: Alexander Graf <graf@amazon.com> Cc: Baoquan He <bhe@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: "Paul E. McKenney" <paulmck@kernel.org> Cc: David Howells <dhowells@redhat.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Guenter Roeck <linux@roeck-us.net> Cc: Ross Zwisler <zwisler@google.com> Cc: Kees Cook <keescook@chromium.org> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> |
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Steven Rostedt (Google)
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be68d63a13 |
ring-buffer: Add ring_buffer_alloc_range()
In preparation to allowing the trace ring buffer to be allocated in a range of memory that is persistent across reboots, add ring_buffer_alloc_range(). It takes a contiguous range of memory and will split it up evenly for the per CPU ring buffers. If there's not enough memory to handle all CPUs with the minimum size, it will fail to allocate the ring buffer. Link: https://lkml.kernel.org/r/20240612232025.363998725@goodmis.org Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Vincent Donnefort <vdonnefort@google.com> Cc: Joel Fernandes <joel@joelfernandes.org> Cc: Daniel Bristot de Oliveira <bristot@redhat.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vineeth Pillai <vineeth@bitbyteword.org> Cc: Youssef Esmat <youssefesmat@google.com> Cc: Beau Belgrave <beaub@linux.microsoft.com> Cc: Alexander Graf <graf@amazon.com> Cc: Baoquan He <bhe@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: "Paul E. McKenney" <paulmck@kernel.org> Cc: David Howells <dhowells@redhat.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Guenter Roeck <linux@roeck-us.net> Cc: Ross Zwisler <zwisler@google.com> Cc: Kees Cook <keescook@chromium.org> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> |
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Steven Rostedt (Google)
|
dd4900d94f |
ring-buffer: Allow mapped field to be set without mapping
In preparation for having the ring buffer mapped to a dedicated location, which will have the same restrictions as user space memory mapped buffers, allow it to use the "mapped" field of the ring_buffer_per_cpu structure without having the user space meta page mapping. When this starts using the mapped field, it will need to handle adding a user space mapping (and removing it) from a ring buffer that is using a dedicated memory range. Link: https://lkml.kernel.org/r/20240612232025.190908567@goodmis.org Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Vincent Donnefort <vdonnefort@google.com> Cc: Joel Fernandes <joel@joelfernandes.org> Cc: Daniel Bristot de Oliveira <bristot@redhat.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vineeth Pillai <vineeth@bitbyteword.org> Cc: Youssef Esmat <youssefesmat@google.com> Cc: Beau Belgrave <beaub@linux.microsoft.com> Cc: Alexander Graf <graf@amazon.com> Cc: Baoquan He <bhe@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: "Paul E. McKenney" <paulmck@kernel.org> Cc: David Howells <dhowells@redhat.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Guenter Roeck <linux@roeck-us.net> Cc: Ross Zwisler <zwisler@google.com> Cc: Kees Cook <keescook@chromium.org> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> |
||
|
Petr Pavlu
|
c2274b908d |
ring-buffer: Fix a race between readers and resize checks
The reader code in rb_get_reader_page() swaps a new reader page into the ring buffer by doing cmpxchg on old->list.prev->next to point it to the new page. Following that, if the operation is successful, old->list.next->prev gets updated too. This means the underlying doubly-linked list is temporarily inconsistent, page->prev->next or page->next->prev might not be equal back to page for some page in the ring buffer. The resize operation in ring_buffer_resize() can be invoked in parallel. It calls rb_check_pages() which can detect the described inconsistency and stop further tracing: [ 190.271762] ------------[ cut here ]------------ [ 190.271771] WARNING: CPU: 1 PID: 6186 at kernel/trace/ring_buffer.c:1467 rb_check_pages.isra.0+0x6a/0xa0 [ 190.271789] Modules linked in: [...] [ 190.271991] Unloaded tainted modules: intel_uncore_frequency(E):1 skx_edac(E):1 [ 190.272002] CPU: 1 PID: 6186 Comm: cmd.sh Kdump: loaded Tainted: G E 6.9.0-rc6-default #5 158d3e1e6d0b091c34c3b96bfd99a1c58306d79f [ 190.272011] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.0-0-gd239552c-rebuilt.opensuse.org 04/01/2014 [ 190.272015] RIP: 0010:rb_check_pages.isra.0+0x6a/0xa0 [ 190.272023] Code: [...] [ 190.272028] RSP: 0018:ffff9c37463abb70 EFLAGS: 00010206 [ 190.272034] RAX: ffff8eba04b6cb80 RBX: 0000000000000007 RCX: ffff8eba01f13d80 [ 190.272038] RDX: ffff8eba01f130c0 RSI: ffff8eba04b6cd00 RDI: ffff8eba0004c700 [ 190.272042] RBP: ffff8eba0004c700 R08: 0000000000010002 R09: 0000000000000000 [ 190.272045] R10: 00000000ffff7f52 R11: ffff8eba7f600000 R12: ffff8eba0004c720 [ 190.272049] R13: ffff8eba00223a00 R14: 0000000000000008 R15: ffff8eba067a8000 [ 190.272053] FS: 00007f1bd64752c0(0000) GS:ffff8eba7f680000(0000) knlGS:0000000000000000 [ 190.272057] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 190.272061] CR2: 00007f1bd6662590 CR3: 000000010291e001 CR4: 0000000000370ef0 [ 190.272070] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 190.272073] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 190.272077] Call Trace: [ 190.272098] <TASK> [ 190.272189] ring_buffer_resize+0x2ab/0x460 [ 190.272199] __tracing_resize_ring_buffer.part.0+0x23/0xa0 [ 190.272206] tracing_resize_ring_buffer+0x65/0x90 [ 190.272216] tracing_entries_write+0x74/0xc0 [ 190.272225] vfs_write+0xf5/0x420 [ 190.272248] ksys_write+0x67/0xe0 [ 190.272256] do_syscall_64+0x82/0x170 [ 190.272363] entry_SYSCALL_64_after_hwframe+0x76/0x7e [ 190.272373] RIP: 0033:0x7f1bd657d263 [ 190.272381] Code: [...] [ 190.272385] RSP: 002b:00007ffe72b643f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 [ 190.272391] RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007f1bd657d263 [ 190.272395] RDX: 0000000000000002 RSI: 0000555a6eb538e0 RDI: 0000000000000001 [ 190.272398] RBP: 0000555a6eb538e0 R08: 000000000000000a R09: 0000000000000000 [ 190.272401] R10: 0000555a6eb55190 R11: 0000000000000246 R12: 00007f1bd6662500 [ 190.272404] R13: 0000000000000002 R14: 00007f1bd6667c00 R15: 0000000000000002 [ 190.272412] </TASK> [ 190.272414] ---[ end trace 0000000000000000 ]--- Note that ring_buffer_resize() calls rb_check_pages() only if the parent trace_buffer has recording disabled. Recent commit |
||
|
Petr Pavlu
|
ea70a9628e |
ring-buffer: Correct stale comments related to non-consuming readers
Adjust the following code documentation: * Kernel-doc comments for ring_buffer_read_prepare() and ring_buffer_read_finish() mention that recording to the ring buffer is disabled when the read is active. Remove mention of this restriction because it was already lifted in commit |
||
|
Steven Rostedt (Google)
|
b9c6820f02 |
ring-buffer: Add cast to unsigned long addr passed to virt_to_page()
The sub-buffer pages are held in an unsigned long array, and when it is
passed to virt_to_page() a cast is needed.
Link: https://lore.kernel.org/all/20240515124808.06279d04@canb.auug.org.au/
Link: https://lore.kernel.org/linux-trace-kernel/20240515010558.4abaefdd@rorschach.local.home
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Fixes:
|
||
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Steven Rostedt (Google)
|
fe832be05a |
ring-buffer: Have mmapped ring buffer keep track of missed events
While testing libtracefs on the mmapped ring buffer, the test that checks if missed events are accounted for failed when using the mapped buffer. This is because the mapped page does not update the missed events that were dropped because the writer filled up the ring buffer before the reader could catch it. Add the missed events to the reader page/sub-buffer when the IOCTL is done and a new reader page is acquired. Note that all accesses to the reader_page via rb_page_commit() had to be switched to rb_page_size(), and rb_page_size() which was just a copy of rb_page_commit() but now it masks out the RB_MISSED bits. This is needed as the mapped reader page is still active in the ring buffer code and where it reads the commit field of the bpage for the size, it now must mask it otherwise the missed bits that are now set will corrupt the size returned. Link: https://lore.kernel.org/linux-trace-kernel/20240312175405.12fb6726@gandalf.local.home Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Vincent Donnefort <vdonnefort@google.com> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> |
||
|
Vincent Donnefort
|
117c39200d |
ring-buffer: Introducing ring-buffer mapping functions
In preparation for allowing the user-space to map a ring-buffer, add
a set of mapping functions:
ring_buffer_{map,unmap}()
And controls on the ring-buffer:
ring_buffer_map_get_reader() /* swap reader and head */
Mapping the ring-buffer also involves:
A unique ID for each subbuf of the ring-buffer, currently they are
only identified through their in-kernel VA.
A meta-page, where are stored ring-buffer statistics and a
description for the current reader
The linear mapping exposes the meta-page, and each subbuf of the
ring-buffer, ordered following their unique ID, assigned during the
first mapping.
Once mapped, no subbuf can get in or out of the ring-buffer: the buffer
size will remain unmodified and the splice enabling functions will in
reality simply memcpy the data instead of swapping subbufs.
Link: https://lore.kernel.org/linux-trace-kernel/20240510140435.3550353-3-vdonnefort@google.com
CC: <linux-mm@kvack.org>
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
Acked-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
|
||
|
Vincent Donnefort
|
c09d4167b5 |
ring-buffer: Allocate sub-buffers with __GFP_COMP
In preparation for the ring-buffer memory mapping, allocate compound pages for the ring-buffer sub-buffers to enable us to map them to user-space with vm_insert_pages(). Link: https://lore.kernel.org/linux-trace-kernel/20240510140435.3550353-2-vdonnefort@google.com Acked-by: David Hildenbrand <david@redhat.com> Signed-off-by: Vincent Donnefort <vdonnefort@google.com> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> |
||
|
Steven Rostedt (Google)
|
ffe3986fec |
ring-buffer: Only update pages_touched when a new page is touched
The "buffer_percent" logic that is used by the ring buffer splice code to
only wake up the tasks when there's no data after the buffer is filled to
the percentage of the "buffer_percent" file is dependent on three
variables that determine the amount of data that is in the ring buffer:
1) pages_read - incremented whenever a new sub-buffer is consumed
2) pages_lost - incremented every time a writer overwrites a sub-buffer
3) pages_touched - incremented when a write goes to a new sub-buffer
The percentage is the calculation of:
(pages_touched - (pages_lost + pages_read)) / nr_pages
Basically, the amount of data is the total number of sub-bufs that have been
touched, minus the number of sub-bufs lost and sub-bufs consumed. This is
divided by the total count to give the buffer percentage. When the
percentage is greater than the value in the "buffer_percent" file, it
wakes up splice readers waiting for that amount.
It was observed that over time, the amount read from the splice was
constantly decreasing the longer the trace was running. That is, if one
asked for 60%, it would read over 60% when it first starts tracing, but
then it would be woken up at under 60% and would slowly decrease the
amount of data read after being woken up, where the amount becomes much
less than the buffer percent.
This was due to an accounting of the pages_touched incrementation. This
value is incremented whenever a writer transfers to a new sub-buffer. But
the place where it was incremented was incorrect. If a writer overflowed
the current sub-buffer it would go to the next one. If it gets preempted
by an interrupt at that time, and the interrupt performs a trace, it too
will end up going to the next sub-buffer. But only one should increment
the counter. Unfortunately, that was not the case.
Change the cmpxchg() that does the real switch of the tail-page into a
try_cmpxchg(), and on success, perform the increment of pages_touched. This
will only increment the counter once for when the writer moves to a new
sub-buffer, and not when there's a race and is incremented for when a
writer and its preempting writer both move to the same new sub-buffer.
Link: https://lore.kernel.org/linux-trace-kernel/20240409151309.0d0e5056@gandalf.local.home
Cc: stable@vger.kernel.org
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Fixes:
|
||
|
Steven Rostedt (Google)
|
b70f293824 |
ring-buffer: Make wake once of ring_buffer_wait() more robust
The default behavior of ring_buffer_wait() when passed a NULL "cond"
parameter is to exit the function the first time it is woken up. The
current implementation uses a counter that starts at zero and when it is
greater than one it exits the wait_event_interruptible().
But this relies on the internal working of wait_event_interruptible() as
that code basically has:
if (cond)
return;
prepare_to_wait();
if (!cond)
schedule();
finish_wait();
That is, cond is called twice before it sleeps. The default cond of
ring_buffer_wait() needs to account for that and wait for its counter to
increment twice before exiting.
Instead, use the seq/atomic_inc logic that is used by the tracing code
that calls this function. Add an atomic_t seq to rb_irq_work and when cond
is NULL, have the default callback take a descriptor as its data that
holds the rbwork and the value of the seq when it started.
The wakeups will now increment the rbwork->seq and the cond callback will
simply check if that number is different, and no longer have to rely on
the implementation of wait_event_interruptible().
Link: https://lore.kernel.org/linux-trace-kernel/20240315063115.6cb5d205@gandalf.local.home
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Fixes:
|
||
 linke li
|
f1e30cb636 |
ring-buffer: use READ_ONCE() to read cpu_buffer->commit_page in concurrent environment
In function ring_buffer_iter_empty(), cpu_buffer->commit_page is read while other threads may change it. It may cause the time_stamp that read in the next line come from a different page. Use READ_ONCE() to avoid having to reason about compiler optimizations now and in future. Link: https://lore.kernel.org/linux-trace-kernel/tencent_DFF7D3561A0686B5E8FC079150A02505180A@qq.com Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: linke li <lilinke99@qq.com> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> |
||
|
Vincent Donnefort
|
6b76323e5a |
ring-buffer: Zero ring-buffer sub-buffers
In preparation for the ring-buffer memory mapping where each subbuf will be accessible to user-space, zero all the page allocations. Link: https://lore.kernel.org/linux-trace-kernel/20240220202310.2489614-2-vdonnefort@google.com Signed-off-by: Vincent Donnefort <vdonnefort@google.com> Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> |
||
 Linus Torvalds
|
63bd30f249 |
Merge tag 'trace-ring-buffer-v6.8-rc7-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
Pull tracing updates from Steven Rostedt: - Do not update shortest_full in rb_watermark_hit() if the watermark is hit. The shortest_full field was being updated regardless if the task was going to wait or not. If the watermark is hit, then the task is not going to wait, so do not update the shortest_full field (used by the waker). - Update shortest_full field before setting the full_waiters_pending flag In the poll logic, the full_waiters_pending flag was being set before the shortest_full field was set. If the full_waiters_pending flag is set, writers will check the shortest_full field which has the least percentage of data that the ring buffer needs to be filled before waking up. The writer will check shortest_full if full_waiters_pending is set, and if the ring buffer percentage filled is greater than shortest full, then it will call the irq_work to wake up the waiters. The problem was that the poll logic set the full_waiters_pending flag before updating shortest_full, which when zero will always trigger the writer to call the irq_work to wake up the waiters. The irq_work will reset the shortest_full field back to zero as the woken waiters is suppose to reset it. - There's some optimized logic in the rb_watermark_hit() that is used in ring_buffer_wait(). Use that helper function in the poll logic as well. - Restructure ring_buffer_wait() to use wait_event_interruptible() The logic to wake up pending readers when the file descriptor is closed is racy. Restructure ring_buffer_wait() to allow callers to pass in conditions besides the ring buffer having enough data in it by using wait_event_interruptible(). - Update the tracing_wait_on_pipe() to call ring_buffer_wait() with its own conditions to exit the wait loop. * tag 'trace-ring-buffer-v6.8-rc7-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: tracing/ring-buffer: Fix wait_on_pipe() race ring-buffer: Use wait_event_interruptible() in ring_buffer_wait() ring-buffer: Reuse rb_watermark_hit() for the poll logic ring-buffer: Fix full_waiters_pending in poll ring-buffer: Do not set shortest_full when full target is hit |
||
|
Steven Rostedt (Google)
|
2aa043a55b |
tracing/ring-buffer: Fix wait_on_pipe() race
When the trace_pipe_raw file is closed, there should be no new readers on
the file descriptor. This is mostly handled with the waking and wait_index
fields of the iterator. But there's still a slight race.
CPU 0 CPU 1
----- -----
wait_index++;
index = wait_index;
ring_buffer_wake_waiters();
wait_on_pipe()
ring_buffer_wait();
The ring_buffer_wait() will miss the wakeup from CPU 1. The problem is
that the ring_buffer_wait() needs the logic of:
prepare_to_wait();
if (!condition)
schedule();
Where the missing condition check is the iter->wait_index update.
Have the ring_buffer_wait() take a conditional callback function and a
data parameter that can be used within the wait_event_interruptible() of
the ring_buffer_wait() function.
In wait_on_pipe(), pass a condition function that will check if the
wait_index has been updated, if it has, it will return true to break out
of the wait_event_interruptible() loop.
Create a new field "closed" in the trace_iterator and set it in the
.flush() callback before calling ring_buffer_wake_waiters().
This will keep any new readers from waiting on a closed file descriptor.
Have the wait_on_pipe() condition callback also check the closed field.
Change the wait_index field of the trace_iterator to atomic_t. There's no
reason it needs to be 'long' and making it atomic and using
atomic_read_acquire() and atomic_fetch_inc_release() will provide the
necessary memory barriers.
Add a "woken" flag to tracing_buffers_splice_read() to exit the loop after
one more try to fetch data. That is, if it waited for data and something
woke it up, it should try to collect any new data and then exit back to
user space.
Link: https://lore.kernel.org/linux-trace-kernel/CAHk-=wgsNgewHFxZAJiAQznwPMqEtQmi1waeS2O1v6L4c_Um5A@mail.gmail.com/
Link: https://lore.kernel.org/linux-trace-kernel/20240312121703.557950713@goodmis.org
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linke li <lilinke99@qq.com>
Cc: Rabin Vincent <rabin@rab.in>
Fixes:
|
||
|
Steven Rostedt (Google)
|
7af9ded0c2 |
ring-buffer: Use wait_event_interruptible() in ring_buffer_wait()
Convert ring_buffer_wait() over to wait_event_interruptible(). The default
condition is to execute the wait loop inside __wait_event() just once.
This does not change the ring_buffer_wait() prototype yet, but
restructures the code so that it can take a "cond" and "data" parameter
and will call wait_event_interruptible() with a helper function as the
condition.
The helper function (rb_wait_cond) takes the cond function and data
parameters. It will first check if the buffer hit the watermark defined by
the "full" parameter and then call the passed in condition parameter. If
either are true, it returns true.
If rb_wait_cond() does not return true, it will set the appropriate
"waiters_pending" flag and returns false.
Link: https://lore.kernel.org/linux-trace-kernel/CAHk-=wgsNgewHFxZAJiAQznwPMqEtQmi1waeS2O1v6L4c_Um5A@mail.gmail.com/
Link: https://lore.kernel.org/linux-trace-kernel/20240312121703.399598519@goodmis.org
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linke li <lilinke99@qq.com>
Cc: Rabin Vincent <rabin@rab.in>
Fixes:
|
||
|
Steven Rostedt (Google)
|
e36f19a645 |
ring-buffer: Reuse rb_watermark_hit() for the poll logic
The check for knowing if the poll should wait or not is basically the exact same logic as rb_watermark_hit(). The only difference is that rb_watermark_hit() also handles the !full case. But for the full case, the logic is the same. Just call that instead of duplicating the code in ring_buffer_poll_wait(). Link: https://lore.kernel.org/linux-trace-kernel/20240312131952.802267543@goodmis.org Cc: Mark Rutland <mark.rutland@arm.com> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> |
||
|
Steven Rostedt (Google)
|
8145f1c35f |
ring-buffer: Fix full_waiters_pending in poll
If a reader of the ring buffer is doing a poll, and waiting for the ring
buffer to hit a specific watermark, there could be a case where it gets
into an infinite ping-pong loop.
The poll code has:
rbwork->full_waiters_pending = true;
if (!cpu_buffer->shortest_full ||
cpu_buffer->shortest_full > full)
cpu_buffer->shortest_full = full;
The writer will see full_waiters_pending and check if the ring buffer is
filled over the percentage of the shortest_full value. If it is, it calls
an irq_work to wake up all the waiters.
But the code could get into a circular loop:
CPU 0 CPU 1
----- -----
[ Poll ]
[ shortest_full = 0 ]
rbwork->full_waiters_pending = true;
if (rbwork->full_waiters_pending &&
[ buffer percent ] > shortest_full) {
rbwork->wakeup_full = true;
[ queue_irqwork ]
cpu_buffer->shortest_full = full;
[ IRQ work ]
if (rbwork->wakeup_full) {
cpu_buffer->shortest_full = 0;
wakeup poll waiters;
[woken]
if ([ buffer percent ] > full)
break;
rbwork->full_waiters_pending = true;
if (rbwork->full_waiters_pending &&
[ buffer percent ] > shortest_full) {
rbwork->wakeup_full = true;
[ queue_irqwork ]
cpu_buffer->shortest_full = full;
[ IRQ work ]
if (rbwork->wakeup_full) {
cpu_buffer->shortest_full = 0;
wakeup poll waiters;
[woken]
[ Wash, rinse, repeat! ]
In the poll, the shortest_full needs to be set before the
full_pending_waiters, as once that is set, the writer will compare the
current shortest_full (which is incorrect) to decide to call the irq_work,
which will reset the shortest_full (expecting the readers to update it).
Also move the setting of full_waiters_pending after the check if the ring
buffer has the required percentage filled. There's no reason to tell the
writer to wake up waiters if there are no waiters.
Link: https://lore.kernel.org/linux-trace-kernel/20240312131952.630922155@goodmis.org
Cc: stable@vger.kernel.org
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Fixes:
|