lkml.org 
[lkml]   [2021]   [Nov]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Subject[BUG] fpga: dfl: possible ABBA deadlock in dfl_fpga_cdev_assign_port() and fme_pr()
Date
Hello,

My static analysis tool reports a possible ABBA deadlock in the dfl
driver in Linux 5.10:

dfl_fpga_cdev_assign_port()
  mutex_lock(&cdev->lock); --> Line 1067 (Lock A)
  mutex_lock(&pdata->lock); --> Line 1624 (Lock B)

fme_pr()
  mutex_lock(&pdata->lock); --> Line 126 (Lock B)
  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: 2021-11-23 08:56    [W:0.133 / U:0.040 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site