https://bugs.kde.org/show_bug.cgi?id=400793
Bug ID: 400793
Summary: pthread_rwlock_timedwrlock false positive
Product: valgrind
Version: 3.14 SVN
Platform: Other
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: helgrind
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
Created attachment 116147
--> https://bugs.kde.org/attachment.cgi?id=116147&action=edit
pthread_rwlock_timedwrlock false positive demo
Unlike drd helgrind demonstrates false positive on timedwrlock.
1. Build example from attach with "gcc test_timedwrlock.c -lpthread"
2. Run under helgrind. Notice error.
--- cut ---
==31157== Helgrind, a thread error detector
==31157== Copyright (C) 2007-2017, and GNU GPL'd, by OpenWorks LLP et al.
==31157== Using Valgrind-3.14.0 and LibVEX; rerun with -h for copyright info
==31157== Command: /tmp/a.out
==31157==
==31157== ---Thread-Announcement------------------------------------------
==31157==
==31157== Thread #2 was created
==31157== at 0x494DAD1: clone (clone.S:87)
==31157== by 0x484E1F2: create_thread (createthread.c:102)
==31157== by 0x484F97B: pthread_create@@GLIBC_2.1 (pthread_create.c:679)
==31157== by 0x4834056: pthread_create_WRK (hg_intercepts.c:427)
==31157== by 0x4834C67: pthread_create@* (hg_intercepts.c:460)
==31157== by 0x1089F6: main (in /tmp/a.out)
==31157==
==31157== ----------------------------------------------------------------
==31157==
==31157== Thread #2 unlocked a not-locked lock at 0x10A080
==31157== at 0x4833963: pthread_rwlock_unlock_WRK (hg_intercepts.c:2540)
==31157== by 0x4835334: pthread_rwlock_unlock (hg_intercepts.c:2559)
==31157== by 0x108947: threadFuncSimple (in /tmp/a.out)
==31157== by 0x48341E1: mythread_wrapper (hg_intercepts.c:389)
==31157== by 0x484F279: start_thread (pthread_create.c:333)
==31157== by 0x494DAE5: clone (clone.S:110)
==31157== Lock at 0x10A080 was first observed
==31157== at 0x48332FD: pthread_rwlock_init_WRK (hg_intercepts.c:2027)
==31157== by 0x48352E6: pthread_rwlock_init (hg_intercepts.c:2042)
==31157== by 0x1089BC: main (in /tmp/a.out)
==31157== Address 0x10a080 is 0 bytes inside data symbol "lock"
==31157==
==31157==
{
<insert_a_suppression_name_here>
Helgrind:UnlockUnlocked
fun:pthread_rwlock_unlock_WRK
fun:pthread_rwlock_unlock
fun:threadFuncSimple
fun:mythread_wrapper
fun:start_thread
fun:clone
}
==31157== ---Thread-Announcement------------------------------------------
==31157==
==31157== Thread #3 was created
==31157== at 0x494DAD1: clone (clone.S:87)
==31157== by 0x484E1F2: create_thread (createthread.c:102)
==31157== by 0x484F97B: pthread_create@@GLIBC_2.1 (pthread_create.c:679)
==31157== by 0x4834056: pthread_create_WRK (hg_intercepts.c:427)
==31157== by 0x4834C67: pthread_create@* (hg_intercepts.c:460)
==31157== by 0x1089F6: main (in /tmp/a.out)
==31157==
==31157== ----------------------------------------------------------------
==31157==
==31157== Possible data race during read of size 4 at 0x10A064 by thread #3
==31157== Locks held: none
==31157== at 0x108911: threadFuncSimple (in /tmp/a.out)
==31157== by 0x48341E1: mythread_wrapper (hg_intercepts.c:389)
==31157== by 0x484F279: start_thread (pthread_create.c:333)
==31157== by 0x494DAE5: clone (clone.S:110)
==31157==
==31157== This conflicts with a previous write of size 4 by thread #2
==31157== Locks held: none
==31157== at 0x10891A: threadFuncSimple (in /tmp/a.out)
==31157== by 0x48341E1: mythread_wrapper (hg_intercepts.c:389)
==31157== by 0x484F279: start_thread (pthread_create.c:333)
==31157== by 0x494DAE5: clone (clone.S:110)
==31157== Address 0x10a064 is 0 bytes inside data symbol "global_a"
==31157==
--- cut ---
3. Run under drd. Notice success.
--- cut ---
==31123== drd, a thread error detector
==31123== Copyright (C) 2006-2017, and GNU GPL'd, by Bart Van Assche.
==31123== Using Valgrind-3.14.0 and LibVEX; rerun with -h for copyright info
==31123== Command: /tmp/a.out
==31123==
global_a = 1
global_a = 2
global_a = 3
global_a = 4
global_a = 5
global_a = 6
global_a = 7
global_a = 8
global_a = 9
Can't lock
Can't lock
Can't lock
Can't lock
Can't lock
Can't lock
global_a = a
==31123==
==31123== For counts of detected and suppressed errors, rerun with: -v
==31123== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 147 from 62)
--- cut ---
Tested libc-pthread versions: 2.23, 2.24. Tested platform: amd64.
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