signal: Use a smaller struct siginfo in the kernel

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We reserve 128 bytes for struct siginfo but only use about 48 bytes on
64bit and 32 bytes on 32bit.  Someday we might use more but it is unlikely
to be anytime soon.

Userspace seems content with just enough bytes of siginfo to implement
sigqueue.  Or in the case of checkpoint/restart reinjecting signals
the kernel has sent.

Reducing the stack footprint and the work to copy siginfo around from
2 cachelines to 1 cachelines seems worth doing even if I don't have
benchmarks to show a performance difference.

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

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This commit is contained in:

Eric W. Biederman 2018-09-25 12:59:31 +02:00

parent ae7795bc61

commit 4ce5f9c9e7

3 changed files with 67 additions and 22 deletions

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2

include/linux/signal.h

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5

include/linux/signal_types.h

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82

kernel/signal.c

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