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authorThomas Gleixner <tglx@linutronix.de>2019-11-06 22:55:37 +0100
committerThomas Gleixner <tglx@linutronix.de>2019-11-20 09:40:07 +0100
commit3d4775df0a89240f671861c6ab6e8d59af8e9e41 (patch)
tree6813a938bd225f703d9569f60eea618a82642e31 /kernel/exit.c
parentba31c1a48538992316cc71ce94fa9cd3e7b427c0 (diff)
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futex: Replace PF_EXITPIDONE with a state
The futex exit handling relies on PF_ flags. That's suboptimal as it requires a smp_mb() and an ugly lock/unlock of the exiting tasks pi_lock in the middle of do_exit() to enforce the observability of PF_EXITING in the futex code. Add a futex_state member to task_struct and convert the PF_EXITPIDONE logic over to the new state. The PF_EXITING dependency will be cleaned up in a later step. This prepares for handling various futex exit issues later. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Ingo Molnar <mingo@kernel.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20191106224556.149449274@linutronix.de
Diffstat (limited to 'kernel/exit.c')
-rw-r--r--kernel/exit.c18
1 files changed, 2 insertions, 16 deletions
diff --git a/kernel/exit.c b/kernel/exit.c
index a46a50d67002..d11bdcaac2e1 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -746,16 +746,7 @@ void __noreturn do_exit(long code)
*/
if (unlikely(tsk->flags & PF_EXITING)) {
pr_alert("Fixing recursive fault but reboot is needed!\n");
- /*
- * We can do this unlocked here. The futex code uses
- * this flag just to verify whether the pi state
- * cleanup has been done or not. In the worst case it
- * loops once more. We pretend that the cleanup was
- * done as there is no way to return. Either the
- * OWNER_DIED bit is set by now or we push the blocked
- * task into the wait for ever nirwana as well.
- */
- tsk->flags |= PF_EXITPIDONE;
+ futex_exit_done(tsk);
set_current_state(TASK_UNINTERRUPTIBLE);
schedule();
}
@@ -846,12 +837,7 @@ void __noreturn do_exit(long code)
* Make sure we are holding no locks:
*/
debug_check_no_locks_held();
- /*
- * We can do this unlocked here. The futex code uses this flag
- * just to verify whether the pi state cleanup has been done
- * or not. In the worst case it loops once more.
- */
- tsk->flags |= PF_EXITPIDONE;
+ futex_exit_done(tsk);
if (tsk->io_context)
exit_io_context(tsk);