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Groups > linux.kernel > #1288734

[PATCH 14/15] dm kcopyd: change mutex to spinlock

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job->lock is only taken for a finite amount of time and the process
doesn't block while holding it, so change it from mutex to spinlock.

This change is needed for the next patch that makes it possible to call
segment_complete from an interrupt. Taking mutexes inside an interrupt is
not allowed.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>

---
 drivers/md/dm-kcopyd.c |   10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

Index: linux-3.16-rc5/drivers/md/dm-kcopyd.c
===================================================================
--- linux-3.16-rc5.orig/drivers/md/dm-kcopyd.c	2014-07-15 19:20:34.000000000 +0200
+++ linux-3.16-rc5/drivers/md/dm-kcopyd.c	2014-07-15 19:24:20.000000000 +0200
@@ -21,7 +21,7 @@
 #include <linux/slab.h>
 #include <linux/vmalloc.h>
 #include <linux/workqueue.h>
-#include <linux/mutex.h>
+#include <linux/spinlock.h>
 #include <linux/delay.h>
 #include <linux/device-mapper.h>
 #include <linux/dm-kcopyd.h>
@@ -356,7 +356,7 @@ struct kcopyd_job {
 	 * These fields are only used if the job has been split
 	 * into more manageable parts.
 	 */
-	struct mutex lock;
+	spinlock_t lock;
 	atomic_t sub_jobs;
 	sector_t progress;
 
@@ -629,7 +629,7 @@ static void segment_complete(int read_er
 	struct kcopyd_job *job = sub_job->master_job;
 	struct dm_kcopyd_client *kc = job->kc;
 
-	mutex_lock(&job->lock);
+	spin_lock(&job->lock);
 
 	/* update the error */
 	if (read_err)
@@ -653,7 +653,7 @@ static void segment_complete(int read_er
 			job->progress += count;
 		}
 	}
-	mutex_unlock(&job->lock);
+	spin_unlock(&job->lock);
 
 	if (count) {
 		int i;
@@ -708,7 +708,7 @@ static void submit_job(struct kcopyd_job
 	if (job->source.count <= SUB_JOB_SIZE)
 		dispatch_job(job);
 	else {
-		mutex_init(&job->lock);
+		spin_lock_init(&job->lock);
 		job->progress = 0;
 		split_job(job);
 	}

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[PATCH 0/15] copy offload patches Mikulas Patocka <mpatocka@redhat.com> - 2015-12-10 18:40 +0100
  [PATCH 7/15] scsi xcopy: keep cache of failures Mikulas Patocka <mpatocka@redhat.com> - 2015-12-10 18:40 +0100
  [PATCH 5/15] block copy: use asynchronous notification Mikulas Patocka <mpatocka@redhat.com> - 2015-12-10 18:40 +0100
  [PATCH 6/15] scsi xcopy: suppress error messages Mikulas Patocka <mpatocka@redhat.com> - 2015-12-10 18:40 +0100
  [PATCH 4/15] block copy: use a timer to fix a theoretical deadlock Mikulas Patocka <mpatocka@redhat.com> - 2015-12-10 18:40 +0100
  [PATCH 14/15] dm kcopyd: change mutex to spinlock Mikulas Patocka <mpatocka@redhat.com> - 2015-12-10 18:40 +0100
  [PATCH 9/15] dm: implement copy Mikulas Patocka <mpatocka@redhat.com> - 2015-12-10 18:40 +0100
  [PATCH 1/15] block copy: initial XCOPY offload support Mikulas Patocka <mpatocka@redhat.com> - 2015-12-10 18:40 +0100
  [PATCH 12/15] dm kcopyd: introduce the function submit_job Mikulas Patocka <mpatocka@redhat.com> - 2015-12-10 18:40 +0100
  Re: [PATCH 0/15] copy offload patches "Martin K. Petersen" <martin.petersen@oracle.com> - 2015-12-10 23:40 +0100
    Re: [dm-devel] [PATCH 0/15] copy offload patches Mike Christie <michaelc@cs.wisc.edu> - 2015-12-11 06:10 +0100
      Re: [dm-devel] [PATCH 0/15] copy offload patches Christoph Hellwig <hch@infradead.org> - 2015-12-11 21:00 +0100

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