Messages in this thread | | | Date | Sun, 11 Jun 2023 06:59:24 -0700 | Subject | Re: [PATCH v2 1/2] scsi: ufs: mcq: Fix the incorrect OCS value for the device command | From | Bart Van Assche <> |
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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.
Thanks,
Bart.
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