diff options
| -rw-r--r-- | fs/dcache.c | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/fs/dcache.c b/fs/dcache.c index 94b737311b61..71969505e82e 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -2564,7 +2564,15 @@ EXPORT_SYMBOL(d_rehash); static inline unsigned start_dir_add(struct inode *dir) { - + /* + * The caller holds a spinlock (dentry::d_lock). On !PREEMPT_RT + * kernels spin_lock() implicitly disables preemption, but not on + * PREEMPT_RT. So for RT it has to be done explicitly to protect + * the sequence count write side critical section against a reader + * or another writer preempting, which would result in a live lock. + */ + if (IS_ENABLED(CONFIG_PREEMPT_RT)) + preempt_disable(); for (;;) { unsigned n = dir->i_dir_seq; if (!(n & 1) && cmpxchg(&dir->i_dir_seq, n, n + 1) == n) @@ -2576,6 +2584,8 @@ static inline unsigned start_dir_add(struct inode *dir) static inline void end_dir_add(struct inode *dir, unsigned n) { smp_store_release(&dir->i_dir_seq, n + 2); + if (IS_ENABLED(CONFIG_PREEMPT_RT)) + preempt_enable(); } static void d_wait_lookup(struct dentry *dentry) |