LU-1282 lprocfs: fix multi-thread contention glitch

[fs/lustre-release.git] / lustre / include / lprocfs_status.h

diff --git a/lustre/include/lprocfs_status.h b/lustre/include/lprocfs_status.h
index 8a2a73d..c8f16b8 100644 (file)
--- a/lustre/include/lprocfs_status.h
+++ b/lustre/include/lprocfs_status.h
@@ -175,9 +175,10 @@ struct lprocfs_percpu {
 #define LPROCFS_GET_SMP_ID  0x0002
 
 enum lprocfs_stats_flags {
-        LPROCFS_STATS_FLAG_NONE     = 0x0000, /* per cpu counter */
-        LPROCFS_STATS_FLAG_NOPERCPU = 0x0001, /* stats have no percpu
-                                               * area and need locking */
+       LPROCFS_STATS_FLAG_NONE     = 0x0000, /* per cpu counter */
+       LPROCFS_STATS_FLAG_NOPERCPU = 0x0001, /* stats have no percpu
+                                              * area and need locking */
+       LPROCFS_STATS_FLAG_IRQ_SAFE = 0x0002, /* alloc need irq safe */
 };
 
 enum lprocfs_fields_flags {
@@ -197,8 +198,9 @@ struct lprocfs_stats {
                                          * been allocated, the 0th entry is
                                          * a statically intialized template */
        int                    ls_flags; /* See LPROCFS_STATS_FLAG_* */
-       cfs_spinlock_t         ls_lock;  /* Lock used only when there are
-                                         * no percpu stats areas */
+       /* Lock used when there are no percpu stats areas; For percpu stats,
+        * it is used to protect ls_biggest_alloc_num change */
+       cfs_spinlock_t         ls_lock;
        struct lprocfs_percpu *ls_percpu[0];
 };
 
@@ -381,31 +383,41 @@ extern int lprocfs_stats_alloc_one(struct lprocfs_stats *stats,
 static inline int lprocfs_stats_lock(struct lprocfs_stats *stats, int opc,
                                     unsigned long *flags)
 {
-       int rc = 0;
+       int             rc = 0;
+       unsigned int    cpuid;
 
        switch (opc) {
        default:
                LBUG();
 
        case LPROCFS_GET_SMP_ID:
-               if (stats->ls_flags & LPROCFS_STATS_FLAG_NOPERCPU) {
-                       cfs_spin_lock_irqsave(&stats->ls_lock, *flags);
-                       return 0;
-               } else {
-                       unsigned int cpuid = cfs_get_cpu();
+               /* percpu counter stats */
+               if ((stats->ls_flags & LPROCFS_STATS_FLAG_NOPERCPU) == 0) {
+                       cpuid = cfs_get_cpu();
 
                        if (unlikely(stats->ls_percpu[cpuid + 1] == NULL))
                                rc = lprocfs_stats_alloc_one(stats, cpuid + 1);
                        return rc < 0 ? rc : cpuid + 1;
                }
 
-       case LPROCFS_GET_NUM_CPU:
-               if (stats->ls_flags & LPROCFS_STATS_FLAG_NOPERCPU) {
+               /* non-percpu counter stats */
+               if ((stats->ls_flags & LPROCFS_STATS_FLAG_IRQ_SAFE) != 0)
                        cfs_spin_lock_irqsave(&stats->ls_lock, *flags);
-                       return 1;
-               } else {
+               else
+                       cfs_spin_lock(&stats->ls_lock);
+               return 0;
+
+       case LPROCFS_GET_NUM_CPU:
+               /* percpu counter stats */
+               if ((stats->ls_flags & LPROCFS_STATS_FLAG_NOPERCPU) == 0)
                        return stats->ls_biggest_alloc_num;
-               }
+
+               /* non-percpu counter stats */
+               if ((stats->ls_flags & LPROCFS_STATS_FLAG_IRQ_SAFE) != 0)
+                       cfs_spin_lock_irqsave(&stats->ls_lock, *flags);
+               else
+                       cfs_spin_lock(&stats->ls_lock);
+               return 1;
        }
 }
 
@@ -417,15 +429,27 @@ static inline void lprocfs_stats_unlock(struct lprocfs_stats *stats, int opc,
                LBUG();
 
        case LPROCFS_GET_SMP_ID:
-               if (stats->ls_flags & LPROCFS_STATS_FLAG_NOPERCPU)
-                       cfs_spin_unlock_irqrestore(&stats->ls_lock, *flags);
-               else
+               if (stats->ls_flags & LPROCFS_STATS_FLAG_NOPERCPU) {
+                       if (stats->ls_flags & LPROCFS_STATS_FLAG_IRQ_SAFE) {
+                               cfs_spin_unlock_irqrestore(&stats->ls_lock,
+                                                          *flags);
+                       } else {
+                               cfs_spin_unlock(&stats->ls_lock);
+                       }
+               } else {
                        cfs_put_cpu();
+               }
                return;
 
        case LPROCFS_GET_NUM_CPU:
-               if (stats->ls_flags & LPROCFS_STATS_FLAG_NOPERCPU)
-                       cfs_spin_unlock_irqrestore(&stats->ls_lock, *flags);
+               if (stats->ls_flags & LPROCFS_STATS_FLAG_NOPERCPU) {
+                       if (stats->ls_flags & LPROCFS_STATS_FLAG_IRQ_SAFE) {
+                               cfs_spin_unlock_irqrestore(&stats->ls_lock,
+                                                          *flags);
+                       } else {
+                               cfs_spin_unlock(&stats->ls_lock);
+                       }
+               }
                return;
        }
 }