aio: wake all waiters when destroying ctx
authorRoland Dreier <roland@purestorage.com>
Tue, 22 Mar 2011 23:35:10 +0000 (16:35 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Wed, 23 Mar 2011 00:44:17 +0000 (17:44 -0700)
commite91f90bb0bb10be9cc8efd09a3cf4ecffcad0db1
treebd9c134e875a3a96a5f96bbde9a112c180ba3d4f
parent77d1c8eb8a8e0989f4c46e9a40bbd4185d34974e
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>
fs/aio.c