Commit cfa92b6d authored by John Stultz's avatar John Stultz Committed by Ingo Molnar

locking/ww_mutex/test: Make sure we bail out instead of livelock

I've seen what appears to be livelocks in the stress_inorder_work()
function, and looking at the code it is clear we can have a case
where we continually retry acquiring the locks and never check to
see if we have passed the specified timeout.

This patch reworks that function so we always check the timeout
before iterating through the loop again.

I believe others may have hit this previously here:

  https://lore.kernel.org/lkml/895ef450-4fb3-5d29-a6ad-790657106a5a@intel.com/Reported-by: default avatarLi Zhijian <zhijianx.li@intel.com>
Signed-off-by: default avatarJohn Stultz <jstultz@google.com>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230922043616.19282-4-jstultz@google.com
parent bccdd808
......@@ -465,17 +465,18 @@ static void stress_inorder_work(struct work_struct *work)
ww_mutex_unlock(&locks[order[n]]);
if (err == -EDEADLK) {
ww_mutex_lock_slow(&locks[order[contended]], &ctx);
goto retry;
if (!time_after(jiffies, stress->timeout)) {
ww_mutex_lock_slow(&locks[order[contended]], &ctx);
goto retry;
}
}
ww_acquire_fini(&ctx);
if (err) {
pr_err_once("stress (%s) failed with %d\n",
__func__, err);
break;
}
ww_acquire_fini(&ctx);
} while (!time_after(jiffies, stress->timeout));
kfree(order);
......
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