Commit a466ca4e authored by Andreas Dilger's avatar Andreas Dilger Committed by Greg Kroah-Hartman
Browse files

staging: lustre: lprocfs: cleanup stats locking code 



Add comment blocks on lprocfs_stats_lock() and lprocfs_stats_unlock().
Move common NOPERCPU code out of the switch() statements to reduce
code size and complexity, since it doesn't depend on the opc at all.

Replace switch() in lprocfs_stats_unlock() with a simple if/else,
since the lock opc was already checked in lprocfs_stats_lock().

Add an enum for the lprocfs_stats_lock() operations to make it clear
what the valid values are and allow compiler checking.

Signed-off-by: default avatarAndreas Dilger <andreas.dilger@intel.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-5946
Reviewed-on: http://review.whamcloud.com/12872


Reviewed-by: default avatarBobi Jam <bobijam@hotmail.com>
Reviewed-by: default avatarJohn L. Hammond <john.hammond@intel.com>
Reviewed-by: default avatarOleg Drokin <oleg.drokin@intel.com>
Signed-off-by: default avatarJames Simmons <jsimmons@infradead.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 6ffc4b3b

drivers/staging/lustre/lustre/include/lprocfs_status.h

+74 −58
Original line number Diff line number Diff line
@@ -165,8 +165,10 @@ struct lprocfs_percpu { 
	struct lprocfs_counter lp_cntr[0];

};



#define LPROCFS_GET_NUM_CPU 0x0001

#define LPROCFS_GET_SMP_ID  0x0002

enum lprocfs_stats_lock_ops {

	LPROCFS_GET_NUM_CPU	= 0x0001, /* number allocated per-CPU stats */

	LPROCFS_GET_SMP_ID	= 0x0002, /* current stat to be updated */

};



enum lprocfs_stats_flags {

	LPROCFS_STATS_FLAG_NONE     = 0x0000, /* per cpu counter */
@@ -371,31 +373,53 @@ int lprocfs_write_frac_helper(const char __user *buffer, 
int lprocfs_read_frac_helper(char *buffer, unsigned long count,

			     long val, int mult);

int lprocfs_stats_alloc_one(struct lprocfs_stats *stats, unsigned int cpuid);

/*

 * \return value

 *      < 0     : on error (only possible for opc as LPROCFS_GET_SMP_ID)



/**

 * Lock statistics structure for access, possibly only on this CPU.

 *

 * The statistics struct may be allocated with per-CPU structures for

 * efficient concurrent update (usually only on server-wide stats), or

 * as a single global struct (e.g. for per-client or per-job statistics),

 * so the required locking depends on the type of structure allocated.

 *

 * For per-CPU statistics, pin the thread to the current cpuid so that

 * will only access the statistics for that CPU.  If the stats structure

 * for the current CPU has not been allocated (or previously freed),

 * allocate it now.  The per-CPU statistics do not need locking since

 * the thread is pinned to the CPU during update.

 *

 * For global statistics, lock the stats structure to prevent concurrent update.

 *

 * \param[in] stats	statistics structure to lock

 * \param[in] opc	type of operation:

 *			LPROCFS_GET_SMP_ID: "lock" and return current CPU index

 *				for incrementing statistics for that CPU

 *			LPROCFS_GET_NUM_CPU: "lock" and return number of used

 *				CPU indices to iterate over all indices

 * \param[out] flags	CPU interrupt saved state for IRQ-safe locking

 *

 * \retval cpuid of current thread or number of allocated structs

 * \retval negative on error (only for opc LPROCFS_GET_SMP_ID + per-CPU stats)

 */

static inline int lprocfs_stats_lock(struct lprocfs_stats *stats, int opc,

static inline int lprocfs_stats_lock(struct lprocfs_stats *stats,

				     enum lprocfs_stats_lock_ops opc,

				     unsigned long *flags)

{

	int		rc = 0;



	switch (opc) {

	default:

		LBUG();



	case LPROCFS_GET_SMP_ID:

	if (stats->ls_flags & LPROCFS_STATS_FLAG_NOPERCPU) {

		if (stats->ls_flags & LPROCFS_STATS_FLAG_IRQ_SAFE)

			spin_lock_irqsave(&stats->ls_lock, *flags);

		else

			spin_lock(&stats->ls_lock);

			return 0;

		} else {

		return opc == LPROCFS_GET_NUM_CPU ? 1 : 0;

	}



	switch (opc) {

	case LPROCFS_GET_SMP_ID: {

		unsigned int cpuid = get_cpu();



		if (unlikely(!stats->ls_percpu[cpuid])) {

				rc = lprocfs_stats_alloc_one(stats, cpuid);

			int rc = lprocfs_stats_alloc_one(stats, cpuid);



			if (rc < 0) {

				put_cpu();

				return rc;
@@ -403,46 +427,38 @@ static inline int lprocfs_stats_lock(struct lprocfs_stats *stats, int opc, 
		}

		return cpuid;

	}



	case LPROCFS_GET_NUM_CPU:

		if (stats->ls_flags & LPROCFS_STATS_FLAG_NOPERCPU) {

			if (stats->ls_flags & LPROCFS_STATS_FLAG_IRQ_SAFE)

				spin_lock_irqsave(&stats->ls_lock, *flags);

			else

				spin_lock(&stats->ls_lock);

			return 1;

		}

		return stats->ls_biggest_alloc_num;

	default:

		LBUG();

	}

}



static inline void lprocfs_stats_unlock(struct lprocfs_stats *stats, int opc,

/**

 * Unlock statistics structure after access.

 *

 * Unlock the lock acquired via lprocfs_stats_lock() for global statistics,

 * or unpin this thread from the current cpuid for per-CPU statistics.

 *

 * This function must be called using the same arguments as used when calling

 * lprocfs_stats_lock() so that the correct operation can be performed.

 *

 * \param[in] stats	statistics structure to unlock

 * \param[in] opc	type of operation (current cpuid or number of structs)

 * \param[in] flags	CPU interrupt saved state for IRQ-safe locking

 */

static inline void lprocfs_stats_unlock(struct lprocfs_stats *stats,

					enum lprocfs_stats_lock_ops opc,

					unsigned long *flags)

{

	switch (opc) {

	default:

		LBUG();



	case LPROCFS_GET_SMP_ID:

	if (stats->ls_flags & LPROCFS_STATS_FLAG_NOPERCPU) {

		if (stats->ls_flags & LPROCFS_STATS_FLAG_IRQ_SAFE)

			spin_unlock_irqrestore(&stats->ls_lock, *flags);

		else

			spin_unlock(&stats->ls_lock);

		} else {

	} else if (opc == LPROCFS_GET_SMP_ID) {

		put_cpu();

	}

		return;



	case LPROCFS_GET_NUM_CPU:

		if (stats->ls_flags & LPROCFS_STATS_FLAG_NOPERCPU) {

			if (stats->ls_flags & LPROCFS_STATS_FLAG_IRQ_SAFE)

				spin_unlock_irqrestore(&stats->ls_lock, *flags);

			else

				spin_unlock(&stats->ls_lock);

		}

		return;

	}

}



static inline unsigned int