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NeilBrown
6326eb4c58
A recent change to clamp_t() in 6.1.y caused fs/nfsd/nfs4state.c to fail to compile with gcc-9. The code in nfsd4_get_drc_mem() was written with the assumption that when "max < min", clamp(val, min, max) would return max. This assumption is not documented as an API promise and the change caused a compile failure if it could be statically determined that "max < min". The relevant code was no longer present upstream when commit1519fbc883("minmax.h: use BUILD_BUG_ON_MSG() for the lo < hi test in clamp()") landed there, so there is no upstream change to nfsd4_get_drc_mem() to backport. There is no clear case that the existing code in nfsd4_get_drc_mem() is functioning incorrectly. The goal of this patch is to permit the clean application of commit1519fbc883("minmax.h: use BUILD_BUG_ON_MSG() for the lo < hi test in clamp()"), and any commits that depend on it, to LTS kernels without affecting the ability to compile those kernels. This is done by open-coding the __clamp() macro sans the built-in type checking. Closes: https://bugzilla.kernel.org/show_bug.cgi?id=220745#c0 Signed-off-by: NeilBrown <neil@brown.name> Stable-dep-of:1519fbc883("minmax.h: use BUILD_BUG_ON_MSG() for the lo < hi test in clamp()") Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Reviewed_by: David Laight <david.laight.linux@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>