| From | Andi Kleen <> | Subject | [PATCH] [221/275] aio: wake all waiters when destroying ctx | Date | Wed, 30 Mar 2011 14:07:46 -0700 (PDT) |
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2.6.35-longterm review patch. If anyone has any objections, please let me know.
------------------ From: Roland Dreier <roland@purestorage.com>
commit e91f90bb0bb10be9cc8efd09a3cf4ecffcad0db1 upstream.
The test program below will hang because io_getevents() uses add_wait_queue_exclusive(), which means the wake_up() in io_destroy() only wakes up one of the threads. Fix this by using wake_up_all() in the aio code paths where we want to make sure no one gets stuck.
// t.c -- compile with gcc -lpthread -laio t.c
#include <libaio.h> #include <pthread.h> #include <stdio.h> #include <unistd.h>
static const int nthr = 2;
void *getev(void *ctx) { struct io_event ev; io_getevents(ctx, 1, 1, &ev, NULL); printf("io_getevents returned\n"); return NULL; }
int main(int argc, char *argv[]) { io_context_t ctx = 0; pthread_t thread[nthr]; int i;
io_setup(1024, &ctx);
for (i = 0; i < nthr; ++i) pthread_create(&thread[i], NULL, getev, ctx);
sleep(1);
io_destroy(ctx);
for (i = 0; i < nthr; ++i) pthread_join(thread[i], NULL);
return 0; }
Signed-off-by: Roland Dreier <roland@purestorage.com> Signed-off-by: Andi Kleen <ak@linux.intel.com> Reviewed-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- fs/aio.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
Index: linux-2.6.35.y/fs/aio.c =================================================================== --- linux-2.6.35.y.orig/fs/aio.c 2011-03-29 22:50:28.449530467 -0700 +++ linux-2.6.35.y/fs/aio.c 2011-03-29 23:03:02.843227419 -0700 @@ -512,7 +512,7 @@ ctx->reqs_active--; if (unlikely(!ctx->reqs_active && ctx->dead)) - wake_up(&ctx->wait); + wake_up_all(&ctx->wait); } static void aio_fput_routine(struct work_struct *data) @@ -1233,7 +1233,7 @@ * by other CPUs at this point. Right now, we rely on the * locking done by the above calls to ensure this consistency. */ - wake_up(&ioctx->wait); + wake_up_all(&ioctx->wait); put_ioctx(ioctx); /* once for the lookup */ }
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