Messages in this thread Patch in this message | | | From | Stanley Chu <> | Date | Sun, 11 Jun 2023 22:49:37 +0800 | Subject | Re: [PATCH v2 1/2] scsi: ufs: mcq: Fix the incorrect OCS value for the device command |
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Hi Bart,
On Sun, Jun 11, 2023 at 10:04 PM Bart Van Assche <bvanassche@acm.org> wrote: > > On 6/9/23 19:15, Po-Wen Kao wrote: > > From: Stanley Chu <stanley.chu@mediatek.com> > > > > In MCQ mode, when a device command uses a hardware queue shared > > with other commands, a race condition may occur in the following scenario: > > > > 1. A device command is completed in CQx with CQE entry "e". > > 2. The interrupt handler copies the "cqe" pointer to "hba->dev_cmd.cqe" > > and completes "hba->dev_cmd.complete". > > 3. The "ufshcd_wait_for_dev_cmd()" function is awakened and retrieves > > the OCS value from "hba->dev_cmd.cqe". > > > > However, there is a possibility that the CQE entry "e" will be overwritten > > by newly completed commands in CQx, resulting in an incorrect OCS value > > being received by "ufshcd_wait_for_dev_cmd()". > > > > To avoid this race condition, the OCS value should be immediately copied > > to the struct "lrb" of the device command. Then "ufshcd_wait_for_dev_cmd()" > > can retrieve the OCS value from the struct "lrb". > > Since with this patch applied ufs_dev_cmd.cqe is always NULL, please > remove the 'cqe' member from struct ufs_dev_cmd.
This patch removes the 'cqe' member from the struct ufs_dev_cmd, as shown in the code section below. Please let us know if anything else has been missed. Very appreciated.
diff --git a/include/ufs/ufshcd.h b/include/ufs/ufshcd.h index 9b2d1859f885..602615e6d1bf 100644 --- a/include/ufs/ufshcd.h +++ b/include/ufs/ufshcd.h @@ -225,7 +225,6 @@ struct ufs_dev_cmd { struct mutex lock; struct completion *complete; struct ufs_query query; - struct cq_entry *cqe; };
Thanks,
Stanley
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