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author | Jason Baron <jbaron@akamai.com> | 2020-04-06 20:11:23 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-04-07 10:43:44 -0700 |
commit | efcdd350d1f8a98fa9fb5280e5af0a22e2059a26 (patch) | |
tree | 679dda708eeafad77d182b70e38f18e5152e513e /usr/gen_initramfs.sh | |
parent | 282144e04b9a88b53dc16dc46e47f7d810e0b63b (diff) | |
download | linux-efcdd350d1f8a98fa9fb5280e5af0a22e2059a26.tar.bz2 |
fs/epoll: make nesting accounting safe for -rt kernel
Davidlohr Bueso pointed out that when CONFIG_DEBUG_LOCK_ALLOC is set
ep_poll_safewake() can take several non-raw spinlocks after disabling
interrupts. Since a spinlock can block in the -rt kernel, we can't take a
spinlock after disabling interrupts. So let's re-work how we determine
the nesting level such that it plays nicely with the -rt kernel.
Let's introduce a 'nests' field in struct eventpoll that records the
current nesting level during ep_poll_callback(). Then, if we nest again
we can find the previous struct eventpoll that we were called from and
increase our count by 1. The 'nests' field is protected by
ep->poll_wait.lock.
I've also moved the visited field to reduce the size of struct eventpoll
from 184 bytes to 176 bytes on x86_64 for !CONFIG_DEBUG_LOCK_ALLOC, which
is typical for a production config.
Reported-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Jason Baron <jbaron@akamai.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Roman Penyaev <rpenyaev@suse.de>
Cc: Eric Wong <normalperson@yhbt.net>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Link: http://lkml.kernel.org/r/1582739816-13167-1-git-send-email-jbaron@akamai.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'usr/gen_initramfs.sh')
0 files changed, 0 insertions, 0 deletions