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Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.6.2 Subject: Re: [PATCH] scsi:target:tcmu: make sure dev blocked before resetting ring Content-Language: en-US To: Guixin Liu , bostroesser@gmail.com, martin.petersen@oracle.com Cc: linux-scsi@vger.kernel.org, target-devel@vger.kernel.org References: <1647417702-129883-1-git-send-email-kanie@linux.alibaba.com> From: Damien Le Moal Organization: Western Digital Research In-Reply-To: <1647417702-129883-1-git-send-email-kanie@linux.alibaba.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: target-devel@vger.kernel.org On 3/16/22 17:01, Guixin Liu wrote: > If dev is not blocked when resetting ring, then there could be new > commands coming in after resetting ring, this will make cmd ring broken, > because tcmu can not find tcmu_cmd when tcmu-runner handled these > newcome commands. > > Signed-off-by: Guixin Liu > --- > drivers/target/target_core_user.c | 14 ++++++++++++-- > 1 file changed, 12 insertions(+), 2 deletions(-) > > diff --git a/drivers/target/target_core_user.c b/drivers/target/target_core_user.c > index 7b2a89a..548ad94 100644 > --- a/drivers/target/target_core_user.c > +++ b/drivers/target/target_core_user.c > @@ -2333,7 +2333,7 @@ static void tcmu_block_dev(struct tcmu_dev *udev) > mutex_unlock(&udev->cmdr_lock); > } > > -static void tcmu_reset_ring(struct tcmu_dev *udev, u8 err_level) > +static int tcmu_reset_ring(struct tcmu_dev *udev, u8 err_level) > { > struct tcmu_mailbox *mb; > struct tcmu_cmd *cmd; > @@ -2341,6 +2341,12 @@ static void tcmu_reset_ring(struct tcmu_dev *udev, u8 err_level) > > mutex_lock(&udev->cmdr_lock); > > + if (!test_bit(TCMU_DEV_BIT_BLOCKED, &udev->flags)) { > + pr_err("The dev should be blocked before resetting ring.\n"); This looks like a bug... So I think this should at least be a WARN_ON(). E.g. if (WARN_ON(!test_bit(TCMU_DEV_BIT_BLOCKED, &udev->flags))) { mutex_unlock(&udev->cmdr_lock); return -EINVAL; } But why is the ring reset even allowed without the device being blocked in the first place ? What is the root cause ? > + mutex_unlock(&udev->cmdr_lock); > + return -EINVAL; > + } > + > xa_for_each(&udev->commands, i, cmd) { > pr_debug("removing cmd %u on dev %s from ring %s\n", > cmd->cmd_id, udev->name, > @@ -2396,6 +2402,7 @@ static void tcmu_reset_ring(struct tcmu_dev *udev, u8 err_level) > run_qfull_queue(udev, false); > > mutex_unlock(&udev->cmdr_lock); > + return 0; > } > > enum { > @@ -2995,7 +3002,10 @@ static ssize_t tcmu_reset_ring_store(struct config_item *item, const char *page, > return -EINVAL; > } > > - tcmu_reset_ring(udev, val); > + ret = tcmu_reset_ring(udev, val); > + if (ret < 0) > + return ret; > + > return count; > } > CONFIGFS_ATTR_WO(tcmu_, reset_ring); -- Damien Le Moal Western Digital Research