diff options
Diffstat (limited to 'features/rt/fs-namespace-Use-cpu_chill-in-trylock-loops.patch')
| -rw-r--r-- | features/rt/fs-namespace-Use-cpu_chill-in-trylock-loops.patch | 43 |
1 files changed, 43 insertions, 0 deletions
diff --git a/features/rt/fs-namespace-Use-cpu_chill-in-trylock-loops.patch b/features/rt/fs-namespace-Use-cpu_chill-in-trylock-loops.patch new file mode 100644 index 00000000..a4536630 --- /dev/null +++ b/features/rt/fs-namespace-Use-cpu_chill-in-trylock-loops.patch @@ -0,0 +1,43 @@ +From 411705d51a89aa7c844f7cae5379a406d720f619 Mon Sep 17 00:00:00 2001 +From: Thomas Gleixner <tglx@linutronix.de> +Date: Wed, 7 Mar 2012 21:00:34 +0100 +Subject: [PATCH 139/191] fs: namespace: Use cpu_chill() in trylock loops + +Retry loops on RT might loop forever when the modifying side was +preempted. Use cpu_chill() instead of cpu_relax() to let the system +make progress. + +Signed-off-by: Thomas Gleixner <tglx@linutronix.de> +--- + fs/namespace.c | 8 ++++++-- + 1 file changed, 6 insertions(+), 2 deletions(-) + +diff --git a/fs/namespace.c b/fs/namespace.c +index 74957d5edaa8..a02b35e791a3 100644 +--- a/fs/namespace.c ++++ b/fs/namespace.c +@@ -14,6 +14,7 @@ + #include <linux/mnt_namespace.h> + #include <linux/user_namespace.h> + #include <linux/namei.h> ++#include <linux/hrtimer.h> + #include <linux/security.h> + #include <linux/cred.h> + #include <linux/idr.h> +@@ -342,8 +343,11 @@ int __mnt_want_write(struct vfsmount *m) + * incremented count after it has set MNT_WRITE_HOLD. + */ + smp_mb(); +- while (READ_ONCE(mnt->mnt.mnt_flags) & MNT_WRITE_HOLD) +- cpu_relax(); ++ while (READ_ONCE(mnt->mnt.mnt_flags) & MNT_WRITE_HOLD) { ++ preempt_enable(); ++ cpu_chill(); ++ preempt_disable(); ++ } + /* + * After the slowpath clears MNT_WRITE_HOLD, mnt_is_readonly will + * be set to match its requirements. So we must not load that until +-- +2.19.1 + |