[Bug 1864864] Re: [SRU] pthread_rwlock_trywrlock results in hang

[Andreas Hasenack]

Test case. Build with:

gcc bug23844.wr.c -lpthread -o bug23844wr


** Attachment added: "bug23844.wr.c"
   https://bugs.launchpad.net/ubuntu/+source/glibc/+bug/1864864/+attachment/5333068/+files/bug23844.wr.c

** Description changed:

  [Impact]
  
-  * pthread_rwlock_trywrlock and pthread_rwlock_tryrdlock before glibc
+  * pthread_rwlock_trywrlock and pthread_rwlock_tryrdlock before glibc
  2.30 could hang:
  https://sourceware.org/bugzilla/show_bug.cgi?id=23844#c14
  
-  * We are especially able to reproduce the problem with BIND 9.16.x when
+  * We are especially able to reproduce the problem with BIND 9.16.x when
  --with-pthread-rwlock configure option enabled
  
-  * But the impact is not limited to BIND 9.16, but any multithreaded
+  * But the impact is not limited to BIND 9.16, but any multithreaded
  application using phtread rwlocks
  
  [Test Case]
  
-  * There's three test cases included in the upstream bugzilla
+ * Fetch the source program and build it:
+ $ wget https://bugs.launchpad.net/ubuntu/+source/glibc/+bug/1864864/+attachment/5333068/+files/bug23844.wr.c
+ $ gcc bug23844.wr.c -lpthread -o bug23844wr
+ 
+ * Run the resulting binary a few times. On affected systems, it should
+ hang in less then 10 attempts.
+ 
+ $ ./bug23844rw
+ trylock_wr
+ 500000
+ 
+ (...)
+ 
+ $ ./bug23844.wr 
+ trylock_wr
+ <hangs>
  
  [Regression Potential]
  
-  * I don't believe there's a chance for regressions here
+  * I don't believe there's a chance for regressions here

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https://bugs.launchpad.net/bugs/1864864

Title:
  [SRU] pthread_rwlock_trywrlock results in hang

Status in glibc package in Ubuntu:
  New
Status in glibc package in Debian:
  Unknown

Bug description:
  [Impact]

   * pthread_rwlock_trywrlock and pthread_rwlock_tryrdlock before glibc
  2.30 could hang:
  https://sourceware.org/bugzilla/show_bug.cgi?id=23844#c14

   * We are especially able to reproduce the problem with BIND 9.16.x
  when --with-pthread-rwlock configure option enabled

   * But the impact is not limited to BIND 9.16, but any multithreaded
  application using phtread rwlocks

  [Test Case]

  * Fetch the source program and build it:
  $ wget https://bugs.launchpad.net/ubuntu/+source/glibc/+bug/1864864/+attachment/5333068/+files/bug23844.wr.c
  $ gcc bug23844.wr.c -lpthread -o bug23844wr

  * Run the resulting binary a few times. On affected systems, it should
  hang in less then 10 attempts.

  $ ./bug23844rw
  trylock_wr
  500000

  (...)

  $ ./bug23844.wr 
  trylock_wr
  <hangs>

  [Regression Potential]

   * I don't believe there's a chance for regressions here

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