2022-11-30 13:21:16

by Li Nan

Subject: [PATCH -next v2 4/9] blk-iocost: read params inside lock in sysfs apis

From: Yu Kuai <[email protected]>

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

Signed-off-by: Yu Kuai <[email protected]>
Signed-off-by: Li Nan <[email protected]>
---
block/blk-iocost.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/block/blk-iocost.c b/block/blk-iocost.c
index bc6522bb314d..3a96cd557c47 100644
--- a/block/blk-iocost.c
+++ b/block/blk-iocost.c
@@ -3125,6 +3125,7 @@ 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,
@@ -3137,6 +3138,7 @@ 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;
}

@@ -3319,12 +3321,14 @@ 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

2022-11-30 20:32:26

by Tejun Heo

Subject: Re: [PATCH -next v2 4/9] blk-iocost: read params inside lock in sysfs apis

On Wed, Nov 30, 2022 at 09:21:51PM +0800, Li Nan wrote:
> From: Yu Kuai <[email protected]>
>
> Otherwise, user might get abnormal values if params is updated
> concurrently.
>
> Signed-off-by: Yu Kuai <[email protected]>
> Signed-off-by: Li Nan <[email protected]>

Acked-by: Tejun Heo <[email protected]>

--
tejun