[v2,1/3] crypto: caam/jr - Remove spinlock for output job ring

Commit Message

Vakul Garg March 15, 2019, 11:25 a.m. UTC

For each job ring pair, the output ring is processed exactly by one cpu
at a time under a tasklet context (one per ring). Therefore, there is no
need to protect a job ring's access & its private data structure using a
lock. Hence the lock can be removed.

Signed-off-by: Vakul Garg <[e-mail]>
---
Changes since v1:
	- Corrected code comment as per Chris Spencer's suggestion

 drivers/crypto/caam/intern.h | 1 -
 drivers/crypto/caam/jr.c     | 7 +------
 2 files changed, 1 insertion(+), 7 deletions(-)

Comments

Horia Geanta March 21, 2019, 4:42 p.m. UTC | #1

On 3/15/2019 1:25 PM, Vakul Garg wrote:
> For each job ring pair, the output ring is processed exactly by one cpu
> at a time under a tasklet context (one per ring). Therefore, there is no
> need to protect a job ring's access & its private data structure using a
> lock. Hence the lock can be removed.
> 
> Signed-off-by: Vakul Garg <[e-mail]>
Reviewed-by: Horia Geantă <[e-mail]>

Thanks,
Horia

Patch

diff --git a/drivers/crypto/caam/intern.h b/drivers/crypto/caam/intern.h
index 30d5b6c5892f..48d62e020599 100644
--- a/drivers/crypto/caam/intern.h
+++ b/drivers/crypto/caam/intern.h
@@ -56,7 +56,6 @@  struct caam_drv_private_jr {
 	u32 inpring_avail;	/* Number of free entries in input ring */
 	int head;			/* entinfo (s/w ring) head index */
 	dma_addr_t *inpring;	/* Base of input ring, alloc DMA-safe */
-	spinlock_t outlock ____cacheline_aligned; /* Output ring index lock */
 	int out_ring_read_index;	/* Output index "tail" */
 	int tail;			/* entinfo (s/w ring) tail index */
 	struct jr_outentry *outring;	/* Base of output ring, DMA-safe */
diff --git a/drivers/crypto/caam/jr.c b/drivers/crypto/caam/jr.c
index b9caa95755d1..d1021026f5b2 100644
--- a/drivers/crypto/caam/jr.c
+++ b/drivers/crypto/caam/jr.c
@@ -177,8 +177,6 @@  static void caam_jr_dequeue(unsigned long devarg)
 
 		head = READ_ONCE(jrp->head);
 
-		spin_lock(&jrp->outlock);
-
 		sw_idx = tail = jrp->tail;
 		hw_idx = jrp->out_ring_read_index;
 
@@ -201,7 +199,7 @@  static void caam_jr_dequeue(unsigned long devarg)
 		/* mark completed, avoid matching on a recycled desc addr */
 		jrp->entinfo[sw_idx].desc_addr_dma = 0;
 
-		/* Stash callback params for use outside of lock */
+		/* Stash callback params */
 		usercall = jrp->entinfo[sw_idx].callbk;
 		userarg = jrp->entinfo[sw_idx].cbkarg;
 		userdesc = jrp->entinfo[sw_idx].desc_addr_virt;
@@ -234,8 +232,6 @@  static void caam_jr_dequeue(unsigned long devarg)
 			jrp->tail = tail;
 		}
 
-		spin_unlock(&jrp->outlock);
-
 		/* Finally, execute user's callback */
 		usercall(dev, userdesc, userstatus, userarg);
 		outring_used--;
@@ -452,7 +448,6 @@  static int caam_jr_init(struct device *dev)
 	jrp->inpring_avail = JOBR_DEPTH;
 
 	spin_lock_init(&jrp->inplock);
-	spin_lock_init(&jrp->outlock);
 
 	/* Select interrupt coalescing parameters */
 	clrsetbits_32(&jrp->rregs->rconfig_lo, 0, JOBR_INTC |