lkml.org 
[lkml]   [2021]   [Nov]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRE: [BUG] fpga: dfl: possible ABBA deadlock in dfl_fpga_cdev_assign_port() and fme_pr()
Date
> 
> dfl_fpga_cdev_assign_port()
>   mutex_lock(&cdev->lock); --> Line 1067 (Lock A)
>   mutex_lock(&pdata->lock); --> Line 1624 (Lock B)

This lock is from port platform device.

>
> fme_pr()
>   mutex_lock(&pdata->lock); --> Line 126 (Lock B)

This lock is from fme platform device.

Actually they are different locks, but yes, maybe we should consider
improving the naming to avoid misunderstanding.

Thanks
Hao

>   fpga_region_program_fpga()
>     fpga_bridges_enable()
>       fpga_bridge_enable()
>         fme_bridge_enable_set() --> function pointer via
> "bridge->br_ops->enable_set()"
>           dfl_fpga_cdev_find_port()
>             mutex_lock(&cdev->lock); --> Line 499 (LockA)
>
> When dfl_fpga_cdev_assign_port() and fme_pr() are concurrently executed,
> the deadlock can occur.
>
> I am not quite sure whether this possible deadlock is real and how to
> fix it if it is real.
> Any feedback would be appreciated, thanks
>
> Reported-by: TOTE Robot <oslab@tsinghua.edu.cn>
>
>
> Best wishes,
> Jia-Ju Bai
\
 
 \ /
  Last update: 2021-11-24 17:01    [W:0.043 / U:0.028 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site