60 lines
1.7 KiB
Diff
60 lines
1.7 KiB
Diff
Subject: fs: dcache: Use cpu_chill() in trylock loops
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From: Thomas Gleixner <tglx@linutronix.de>
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Date: Wed, 07 Mar 2012 21:00:34 +0100
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Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.18/older/patches-4.18.5-rt3.tar.xz
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Retry loops on RT might loop forever when the modifying side was
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preempted. Use cpu_chill() instead of cpu_relax() to let the system
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make progress.
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Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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---
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fs/autofs/expire.c | 3 ++-
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fs/namespace.c | 8 ++++++--
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2 files changed, 8 insertions(+), 3 deletions(-)
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--- a/fs/autofs/expire.c
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+++ b/fs/autofs/expire.c
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@@ -8,6 +8,7 @@
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* option, any later version, incorporated herein by reference.
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*/
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+#include <linux/delay.h>
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#include "autofs_i.h"
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static unsigned long now;
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@@ -148,7 +149,7 @@ static struct dentry *get_next_positive_
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parent = p->d_parent;
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if (!spin_trylock(&parent->d_lock)) {
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spin_unlock(&p->d_lock);
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- cpu_relax();
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+ cpu_chill();
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goto relock;
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}
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spin_unlock(&p->d_lock);
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--- a/fs/namespace.c
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+++ b/fs/namespace.c
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@@ -14,6 +14,7 @@
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#include <linux/mnt_namespace.h>
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#include <linux/user_namespace.h>
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#include <linux/namei.h>
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+#include <linux/delay.h>
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#include <linux/security.h>
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#include <linux/cred.h>
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#include <linux/idr.h>
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@@ -353,8 +354,11 @@ int __mnt_want_write(struct vfsmount *m)
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* incremented count after it has set MNT_WRITE_HOLD.
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*/
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smp_mb();
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- while (READ_ONCE(mnt->mnt.mnt_flags) & MNT_WRITE_HOLD)
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- cpu_relax();
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+ while (READ_ONCE(mnt->mnt.mnt_flags) & MNT_WRITE_HOLD) {
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+ preempt_enable();
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+ cpu_chill();
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+ preempt_disable();
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+ }
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/*
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* After the slowpath clears MNT_WRITE_HOLD, mnt_is_readonly will
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* be set to match its requirements. So we must not load that until
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