[lwip-devel] [bug #19168] pbuf_free can cause deadlock

[Dmitry Potapov]

URL:
  <http://savannah.nongnu.org/bugs/?19168>

                 Summary: pbuf_free can cause deadlock
                 Project: lwIP - A Lightweight TCP/IP stack
            Submitted by: dpotapov
            Submitted on: Wednesday 02/28/2007 at 10:19
                Category: pbufs
                Severity: 3 - Normal
              Item Group: Crash Error
                  Status: None
                 Privacy: Public
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any

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Details:

pbuf_free uses SYS_ARCH_PROTECT at the beginning, which could be implemented
by disabling interrupts for an embedded system, after that it calls either
PBUF_POOL_FREE(), or memp_free(), or mem_free().

mem_free() always calls to sys_sem_wait(mem_sem);
PBUF_POOL_FREE() and memp_free() uses sys_sem_wait() if
SYS_LIGHTWEIGHT_PROT = 0

As result, deadlock may happen because interrupts are disabled, so the thread
that holds semaphore will never released it.

I have attached the patch



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File Attachments:


-------------------------------------------------------
Date: Wednesday 02/28/2007 at 10:19  Name: pbuf_free.patch  Size: 2kB   By:
dpotapov

<http://savannah.nongnu.org/bugs/download.php?file_id=12058>

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