[PATCH v4 3/5] blk-iocost: read params inside lock in sysfs apis

[Yu Kuai]

From: Yu Kuai <yukuai3@xxxxxxxxxx>

Otherwise, user might get abnormal values if params is updated
concurrently.

Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
Acked-by: Tejun Heo <tj@xxxxxxxxxx>
---
 block/blk-iocost.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/block/blk-iocost.c b/block/blk-iocost.c
index d6256731cae4..d6f692d2283c 100644
--- a/block/blk-iocost.c
+++ b/block/blk-iocost.c
@@ -3129,6 +3129,7 @@ static u64 ioc_qos_prfill(struct seq_file *sf, struct blkg_policy_data *pd,
 	if (!dname)
 		return 0;
 
+	spin_lock_irq(&ioc->lock);
 	seq_printf(sf, "%s enable=%d ctrl=%s rpct=%u.%02u rlat=%u wpct=%u.%02u wlat=%u min=%u.%02u max=%u.%02u\n",
 		   dname, ioc->enabled, ioc->user_qos_params ? "user" : "auto",
 		   ioc->params.qos[QOS_RPPM] / 10000,
@@ -3141,6 +3142,7 @@ static u64 ioc_qos_prfill(struct seq_file *sf, struct blkg_policy_data *pd,
 		   ioc->params.qos[QOS_MIN] % 10000 / 100,
 		   ioc->params.qos[QOS_MAX] / 10000,
 		   ioc->params.qos[QOS_MAX] % 10000 / 100);
+	spin_unlock_irq(&ioc->lock);
 	return 0;
 }
 
@@ -3320,12 +3322,14 @@ static u64 ioc_cost_model_prfill(struct seq_file *sf,
 	if (!dname)
 		return 0;
 
+	spin_lock_irq(&ioc->lock);
 	seq_printf(sf, "%s ctrl=%s model=linear "
 		   "rbps=%llu rseqiops=%llu rrandiops=%llu "
 		   "wbps=%llu wseqiops=%llu wrandiops=%llu\n",
 		   dname, ioc->user_cost_model ? "user" : "auto",
 		   u[I_LCOEF_RBPS], u[I_LCOEF_RSEQIOPS], u[I_LCOEF_RRANDIOPS],
 		   u[I_LCOEF_WBPS], u[I_LCOEF_WSEQIOPS], u[I_LCOEF_WRANDIOPS]);
+	spin_unlock_irq(&ioc->lock);
 	return 0;
 }
 
-- 
2.31.1