aio: wake all waiters when destroying ctx
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>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/aio.c b/fs/aio.c
index 7f54f43..ebb6a22 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -520,7 +520,7 @@
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)
@@ -1229,7 +1229,7 @@
* 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 */
}