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Subject[PATCH 6/9] staging: lustre: libcfs: add lock-class for cfs_percpt_lock
Date
From: Liang Zhen <liang.zhen@intel.com>

initialise lock-class for each sublock of cfs_percpt_lock
to eliminate false alarm ""possible recursive locking detected"

Signed-off-by: Liang Zhen <liang.zhen@intel.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-6432
Reviewed-on: http://review.whamcloud.com/14368
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
---
.../lustre/include/linux/libcfs/libcfs_cpu.h | 19 +++++++++++++++++--
drivers/staging/lustre/lnet/libcfs/libcfs_lock.c | 13 ++++++++++---
2 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/drivers/staging/lustre/include/linux/libcfs/libcfs_cpu.h b/drivers/staging/lustre/include/linux/libcfs/libcfs_cpu.h
index 71ad93b..81d8079 100644
--- a/drivers/staging/lustre/include/linux/libcfs/libcfs_cpu.h
+++ b/drivers/staging/lustre/include/linux/libcfs/libcfs_cpu.h
@@ -256,8 +256,8 @@ struct cfs_percpt_lock {
* create a cpu-partition lock based on CPU partition table \a cptab,
* each private lock has extra \a psize bytes padding data
*/
-struct cfs_percpt_lock *cfs_percpt_lock_alloc(struct cfs_cpt_table *cptab);
-
+struct cfs_percpt_lock *cfs_percpt_lock_create(struct cfs_cpt_table *cptab,
+ struct lock_class_key *keys);
/* destroy a cpu-partition lock */
void cfs_percpt_lock_free(struct cfs_percpt_lock *pcl);

@@ -267,6 +267,21 @@ void cfs_percpt_lock(struct cfs_percpt_lock *pcl, int index);
/* unlock private lock \a index of \a pcl */
void cfs_percpt_unlock(struct cfs_percpt_lock *pcl, int index);

+#define CFS_PERCPT_LOCK_KEYS 256
+
+/* NB: don't allocate keys dynamically, lockdep needs them to be in ".data" */
+#define cfs_percpt_lock_alloc(cptab) \
+({ \
+ static struct lock_class_key ___keys[CFS_PERCPT_LOCK_KEYS]; \
+ struct cfs_percpt_lock *___lk; \
+ \
+ if (cfs_cpt_number(cptab) > CFS_PERCPT_LOCK_KEYS) \
+ ___lk = cfs_percpt_lock_create(cptab, NULL); \
+ else \
+ ___lk = cfs_percpt_lock_create(cptab, ___keys); \
+ ___lk; \
+})
+
/**
* iterate over all CPU partitions in \a cptab
*/
diff --git a/drivers/staging/lustre/lnet/libcfs/libcfs_lock.c b/drivers/staging/lustre/lnet/libcfs/libcfs_lock.c
index d38954a..83543f9 100644
--- a/drivers/staging/lustre/lnet/libcfs/libcfs_lock.c
+++ b/drivers/staging/lustre/lnet/libcfs/libcfs_lock.c
@@ -49,7 +49,8 @@ EXPORT_SYMBOL(cfs_percpt_lock_free);
* reason we always allocate cacheline-aligned memory block.
*/
struct cfs_percpt_lock *
-cfs_percpt_lock_alloc(struct cfs_cpt_table *cptab)
+cfs_percpt_lock_create(struct cfs_cpt_table *cptab,
+ struct lock_class_key *keys)
{
struct cfs_percpt_lock *pcl;
spinlock_t *lock;
@@ -67,12 +68,18 @@ cfs_percpt_lock_alloc(struct cfs_cpt_table *cptab)
return NULL;
}

- cfs_percpt_for_each(lock, i, pcl->pcl_locks)
+ if (!keys)
+ CWARN("Cannot setup class key for percpt lock, you may see recursive locking warnings which are actually fake.\n");
+
+ cfs_percpt_for_each(lock, i, pcl->pcl_locks) {
spin_lock_init(lock);
+ if (keys != NULL)
+ lockdep_set_class(lock, &keys[i]);
+ }

return pcl;
}
-EXPORT_SYMBOL(cfs_percpt_lock_alloc);
+EXPORT_SYMBOL(cfs_percpt_lock_create);

/**
* lock a CPU partition
--
1.7.1
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