[PATCH v2 5/5] blk-iocost: read params inside lock in sysfs apis

Yu Kuai
2022-11-04T02:18:23Z

From: Yu Kuai <yukuai3@huawei.com>

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

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
---
block/blk-iocost.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/block/blk-iocost.c b/block/blk-iocost.c
index 192ad4e0cfc6..7d682ce0bee6 100644
--- a/block/blk-iocost.c
+++ b/block/blk-iocost.c
@@ -3135,6 +3135,7 @@ static u64 ioc_qos_prfill(struct seq_file *sf, struct blkg_policy_data *pd,
if (!dname)
return 0;

+ mutex_lock(&ioc->params_mutex);
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,
@@ -3147,6 +3148,7 @@ 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);
+ mutex_unlock(&ioc->params_mutex);
return 0;
}

@@ -3331,12 +3333,14 @@ static u64 ioc_cost_model_prfill(struct seq_file *sf,
if (!dname)
return 0;

+ mutex_lock(&ioc->params_mutex);
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]);
+ mutex_unlock(&ioc->params_mutex);
return 0;
}

--
2.31.1