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authorLinus Torvalds <torvalds@linux-foundation.org>2019-11-26 16:02:40 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2019-11-26 16:02:40 -0800
commit168829ad09ca9cdfdc664b2110d0e3569932c12d (patch)
tree1b6351ab5766a272dec1fc08f77272a199bba978 /kernel/exit.c
parent1ae78780eda54023a0fb49ee743dbba39da148e0 (diff)
parent500543c53a54134ced386aed85cd93cf1363f981 (diff)
Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking updates from Ingo Molnar: "The main changes in this cycle were: - A comprehensive rewrite of the robust/PI futex code's exit handling to fix various exit races. (Thomas Gleixner et al) - Rework the generic REFCOUNT_FULL implementation using atomic_fetch_* operations so that the performance impact of the cmpxchg() loops is mitigated for common refcount operations. With these performance improvements the generic implementation of refcount_t should be good enough for everybody - and this got confirmed by performance testing, so remove ARCH_HAS_REFCOUNT and REFCOUNT_FULL entirely, leaving the generic implementation enabled unconditionally. (Will Deacon) - Other misc changes, fixes, cleanups" * 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (27 commits) lkdtm: Remove references to CONFIG_REFCOUNT_FULL locking/refcount: Remove unused 'refcount_error_report()' function locking/refcount: Consolidate implementations of refcount_t locking/refcount: Consolidate REFCOUNT_{MAX,SATURATED} definitions locking/refcount: Move saturation warnings out of line locking/refcount: Improve performance of generic REFCOUNT_FULL code locking/refcount: Move the bulk of the REFCOUNT_FULL implementation into the <linux/refcount.h> header locking/refcount: Remove unused refcount_*_checked() variants locking/refcount: Ensure integer operands are treated as signed locking/refcount: Define constants for saturation and max refcount values futex: Prevent exit livelock futex: Provide distinct return value when owner is exiting futex: Add mutex around futex exit futex: Provide state handling for exec() as well futex: Sanitize exit state handling futex: Mark the begin of futex exit explicitly futex: Set task::futex_state to DEAD right after handling futex exit futex: Split futex_mm_release() for exit/exec exit/exec: Seperate mm_release() futex: Replace PF_EXITPIDONE with a state ...
Diffstat (limited to 'kernel/exit.c')
-rw-r--r--kernel/exit.c30
1 files changed, 2 insertions, 28 deletions
diff --git a/kernel/exit.c b/kernel/exit.c
index f2d20ab74422..0bac4b60d5f3 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -437,7 +437,7 @@ static void exit_mm(void)
struct mm_struct *mm = current->mm;
struct core_state *core_state;
- mm_release(current, mm);
+ exit_mm_release(current, mm);
if (!mm)
return;
sync_mm_rss(mm);
@@ -746,32 +746,12 @@ 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_recursive(tsk);
set_current_state(TASK_UNINTERRUPTIBLE);
schedule();
}
exit_signals(tsk); /* sets PF_EXITING */
- /*
- * Ensure that all new tsk->pi_lock acquisitions must observe
- * PF_EXITING. Serializes against futex.c:attach_to_pi_owner().
- */
- smp_mb();
- /*
- * Ensure that we must observe the pi_state in exit_mm() ->
- * mm_release() -> exit_pi_state_list().
- */
- raw_spin_lock_irq(&tsk->pi_lock);
- raw_spin_unlock_irq(&tsk->pi_lock);
if (unlikely(in_atomic())) {
pr_info("note: %s[%d] exited with preempt_count %d\n",
@@ -846,12 +826,6 @@ 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;
if (tsk->io_context)
exit_io_context(tsk);