Bart Van Assche ac1bc2ba06 scsi: ufs: Request sense data asynchronously
Clearing a unit attention synchronously from inside the UFS error handler
may trigger the following deadlock:

 - ufshcd_err_handler() calls ufshcd_err_handling_unprepare() and the
   latter function calls ufshcd_clear_ua_wluns().

 - ufshcd_clear_ua_wluns() submits a REQUEST SENSE command and that command
   activates the SCSI error handler.

 - The SCSI error handler calls ufshcd_host_reset_and_restore().

 - ufshcd_host_reset_and_restore() executes the following code:
   ufshcd_schedule_eh_work(hba); flush_work(&hba->eh_work);

This sequence results in a deadlock (circular wait). Fix this by requesting
sense data asynchronously.

Link: https://lore.kernel.org/r/20210722033439.26550-16-bvanassche@acm.org
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Stanley Chu <stanley.chu@mediatek.com>
Cc: Can Guo <cang@codeaurora.org>
Cc: Asutosh Das <asutoshd@codeaurora.org>
Cc: Avri Altman <avri.altman@wdc.com>
Reviewed-by: Bean Huo <beanhuo@micron.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2021-08-02 21:43:59 -04:00
2021-07-18 14:13:49 -07:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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