blk-iocost: read params inside lock in sysfs apis

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

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20230117070806.3857142-4-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-iocost.c b/block/blk-iocost.c
index 42a4920..58ad4e5 100644 (file)
--- a/block/blk-iocost.c
+++ b/block/blk-iocost.c
@@ -3131,6 +3131,7 @@ 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,
@@ -3143,6 +3144,7 @@ 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;
 }
 
@@ -3322,12 +3324,14 @@ 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;
 }