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authorYu Kuai <yukuai3@huawei.com>2022-10-12 17:40:33 +0800
committerJens Axboe <axboe@kernel.dk>2022-10-23 18:59:16 -0600
commit2c0647988433c3d7120542a3c42e12c152dd7afc (patch)
treecef849c727459bc92fa9d114d9cd0fe53285d7ee /block/blk-iocost.c
parent8796acbc9a0eceeddd99eaef833bdda1241d39b9 (diff)
blk-iocost: don't release 'ioc->lock' while updating params
ioc_qos_write() and ioc_cost_model_write() are the same: 1) hold lock to read 'ioc->params' to local variable; 2) update params to local variable without lock; 3) hold lock to write local variable to 'ioc->params'; In theroy, if user updates params concurrenty, the params might be lost: t1: update params a t2: update params b spin_lock_irq(&ioc->lock); memcpy(qos, ioc->params.qos, sizeof(qos)) spin_unlock_irq(&ioc->lock); qos[a] = xxx; spin_lock_irq(&ioc->lock); memcpy(qos, ioc->params.qos, sizeof(qos)) spin_unlock_irq(&ioc->lock); qos[b] = xxx; spin_lock_irq(&ioc->lock); memcpy(ioc->params.qos, qos, sizeof(qos)); ioc_refresh_params(ioc, true); spin_unlock_irq(&ioc->lock); spin_lock_irq(&ioc->lock); // updates of a will be lost memcpy(ioc->params.qos, qos, sizeof(qos)); ioc_refresh_params(ioc, true); spin_unlock_irq(&ioc->lock); Althrough this is not common case, the problem can by fixed easily by holding the lock through the read, update, write process. Signed-off-by: Yu Kuai <yukuai3@huawei.com> Acked-by: Tejun Heo <tj@kernel.org> Link: https://lore.kernel.org/r/20221012094035.390056-3-yukuai1@huaweicloud.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/blk-iocost.c')
-rw-r--r--block/blk-iocost.c7
1 files changed, 2 insertions, 5 deletions
diff --git a/block/blk-iocost.c b/block/blk-iocost.c
index 08036476e6fa..6d36a4bd4382 100644
--- a/block/blk-iocost.c
+++ b/block/blk-iocost.c
@@ -3191,7 +3191,6 @@ static ssize_t ioc_qos_write(struct kernfs_open_file *of, char *input,
memcpy(qos, ioc->params.qos, sizeof(qos));
enable = ioc->enabled;
user = ioc->user_qos_params;
- spin_unlock_irq(&ioc->lock);
while ((p = strsep(&input, " \t\n"))) {
substring_t args[MAX_OPT_ARGS];
@@ -3258,8 +3257,6 @@ static ssize_t ioc_qos_write(struct kernfs_open_file *of, char *input,
if (qos[QOS_MIN] > qos[QOS_MAX])
goto einval;
- spin_lock_irq(&ioc->lock);
-
if (enable) {
blk_stat_enable_accounting(disk->queue);
blk_queue_flag_set(QUEUE_FLAG_RQ_ALLOC_TIME, disk->queue);
@@ -3284,6 +3281,7 @@ static ssize_t ioc_qos_write(struct kernfs_open_file *of, char *input,
blkdev_put_no_open(bdev);
return nbytes;
einval:
+ spin_unlock_irq(&ioc->lock);
ret = -EINVAL;
err:
blkdev_put_no_open(bdev);
@@ -3359,7 +3357,6 @@ static ssize_t ioc_cost_model_write(struct kernfs_open_file *of, char *input,
spin_lock_irq(&ioc->lock);
memcpy(u, ioc->params.i_lcoefs, sizeof(u));
user = ioc->user_cost_model;
- spin_unlock_irq(&ioc->lock);
while ((p = strsep(&input, " \t\n"))) {
substring_t args[MAX_OPT_ARGS];
@@ -3396,7 +3393,6 @@ static ssize_t ioc_cost_model_write(struct kernfs_open_file *of, char *input,
user = true;
}
- spin_lock_irq(&ioc->lock);
if (user) {
memcpy(ioc->params.i_lcoefs, u, sizeof(u));
ioc->user_cost_model = true;
@@ -3410,6 +3406,7 @@ static ssize_t ioc_cost_model_write(struct kernfs_open_file *of, char *input,
return nbytes;
einval:
+ spin_unlock_irq(&ioc->lock);
ret = -EINVAL;
err:
blkdev_put_no_open(bdev);