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Commit f946add8 authored by Sebastian Andrzej Siewior's avatar Sebastian Andrzej Siewior Committed by Harshit Jain
Browse files

zram: Allocate struct zcomp_strm as per-CPU memory 



zcomp::stream is a per-CPU pointer, pointing to struct zcomp_strm
which contains two pointers. Having struct zcomp_strm allocated
directly as per-CPU memory would avoid one additional memory
allocation and a pointer dereference. This also simplifies the
addition of a local_lock to struct zcomp_strm.

Allocate zcomp::stream directly as per-CPU memory.

Signed-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Acked-by: default avatarPeter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20200527201119.1692513-7-bigeasy@linutronix.de
parent 41caa1d5

drivers/block/zram/zcomp.c

+16 −25
Original line number Diff line number Diff line
@@ -42,19 +42,16 @@ static void zcomp_strm_free(struct zcomp_strm *zstrm) 
	if (!IS_ERR_OR_NULL(zstrm->tfm))

		crypto_free_comp(zstrm->tfm);

	free_pages((unsigned long)zstrm->buffer, 1);

	kfree(zstrm);

	zstrm->tfm = NULL;

	zstrm->buffer = NULL;

}



/*

 * allocate new zcomp_strm structure with ->tfm initialized by

 * backend, return NULL on error

 * Initialize zcomp_strm structure with ->tfm initialized by backend, and

 * ->buffer. Return a negative value on error.

 */

static struct zcomp_strm *zcomp_strm_alloc(struct zcomp *comp)

static int zcomp_strm_init(struct zcomp_strm *zstrm, struct zcomp *comp)

{

	struct zcomp_strm *zstrm = kmalloc(sizeof(*zstrm), GFP_KERNEL);

	if (!zstrm)

		return NULL;



	zstrm->tfm = crypto_alloc_comp(comp->name, 0, 0);

	/*

	 * allocate 2 pages. 1 for compressed data, plus 1 extra for the
@@ -63,9 +60,9 @@ static struct zcomp_strm *zcomp_strm_alloc(struct zcomp *comp) 
	zstrm->buffer = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 1);

	if (IS_ERR_OR_NULL(zstrm->tfm) || !zstrm->buffer) {

		zcomp_strm_free(zstrm);

		zstrm = NULL;

		return -ENOMEM;

	}

	return zstrm;

	return 0;

}



bool zcomp_available_algorithm(const char *comp)
@@ -118,7 +115,7 @@ ssize_t zcomp_available_show(const char *comp, char *buf) 


struct zcomp_strm *zcomp_stream_get(struct zcomp *comp)

{

	return *get_cpu_ptr(comp->stream);

	return get_cpu_ptr(comp->stream);

}



void zcomp_stream_put(struct zcomp *comp)
@@ -164,17 +161,13 @@ int zcomp_cpu_up_prepare(unsigned int cpu, struct hlist_node *node) 
{

	struct zcomp *comp = hlist_entry(node, struct zcomp, node);

	struct zcomp_strm *zstrm;

	int ret;



	if (WARN_ON(*per_cpu_ptr(comp->stream, cpu)))

		return 0;



	zstrm = zcomp_strm_alloc(comp);

	if (IS_ERR_OR_NULL(zstrm)) {

	zstrm = per_cpu_ptr(comp->stream, cpu);

	ret = zcomp_strm_init(zstrm, comp);

	if (ret)

		pr_err("Can't allocate a compression stream\n");

		return -ENOMEM;

	}

	*per_cpu_ptr(comp->stream, cpu) = zstrm;

	return 0;

	return ret;

}



int zcomp_cpu_dead(unsigned int cpu, struct hlist_node *node)
@@ -182,10 +175,8 @@ int zcomp_cpu_dead(unsigned int cpu, struct hlist_node *node) 
	struct zcomp *comp = hlist_entry(node, struct zcomp, node);

	struct zcomp_strm *zstrm;



	zstrm = *per_cpu_ptr(comp->stream, cpu);

	if (!IS_ERR_OR_NULL(zstrm))

	zstrm = per_cpu_ptr(comp->stream, cpu);

	zcomp_strm_free(zstrm);

	*per_cpu_ptr(comp->stream, cpu) = NULL;

	return 0;

}
@@ -193,7 +184,7 @@ static int zcomp_init(struct zcomp *comp) 
{

	int ret;



	comp->stream = alloc_percpu(struct zcomp_strm *);

	comp->stream = alloc_percpu(struct zcomp_strm);

	if (!comp->stream)

		return -ENOMEM;

drivers/block/zram/zcomp.h

+1 −1
Original line number Diff line number Diff line
@@ -18,7 +18,7 @@ struct zcomp_strm { 


/* dynamic per-device compression frontend */

struct zcomp {

	struct zcomp_strm * __percpu *stream;

	struct zcomp_strm __percpu *stream;

	const char *name;

	struct hlist_node node;

};