This has been initially reported at: https://bugzilla.suse.com/show_bug.cgi?id=923486 OpenSUSE team found an intermittent issue with pthread's rwlock functions while running the tests from findutils. test_twlock was reporting different values for check_accounts: === trial: 24: failure: 0 Starting test_lock ... OK Starting test_rwlock ...check_accounts: sum=4006, expected 4000 check_accounts: sum=4006, expected 4000 check_accounts: sum=4006, expected 4000 check_accounts: sum=4006, expected 4000 Aborted (core dumped) === trial: 25: failure: 1 === trial: 616: failure: 29 Starting test_lock ... OK Starting test_rwlock ...check_accounts: sum=3994, expected 4000 check_accounts: sum=3994, expected 4000 check_accounts: sum=3994, expected 4000 check_accounts: sum=3994, expected 4000 Aborted (core dumped) === trial: 617: failure: 30 === trial: 866: failure: 39
This is an automated email from the git hooks/post-receive script. It was generated because a ref change was pushed to the repository containing the project "GNU C Library master sources". The branch, master has been updated via 6ec52bf634b7650b57ff67b5f5053bce8992d549 (commit) from 44f826e317f28969ea6ca0e87aa4c6b69c819245 (commit) Those revisions listed above that are new to this repository have not appeared on any other notification email; so we list those revisions in full, below. - Log ----------------------------------------------------------------- https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=6ec52bf634b7650b57ff67b5f5053bce8992d549 commit 6ec52bf634b7650b57ff67b5f5053bce8992d549 Author: Tulio Magno Quites Machado Filho <tuliom@linux.vnet.ibm.com> Date: Wed Jul 22 09:26:02 2015 -0300 PowerPC: Fix a race condition when eliding a lock The previous code used to evaluate the preprocessor token is_lock_free to a variable before starting a transaction. This behavior can cause an error if another thread got the lock (without using a transaction) between the evaluation of the token and the beginning of the transaction. This bug can be triggered with the following order of events: 1. The lock accessed by is_lock_free is free. 2. Thread T1 evaluates is_lock_free and stores into register R1 that the lock is free. 3. Thread T2 acquires the same lock used in is_lock_free. 4. T1 begins the transaction, creating a memory barrier where is_lock_free is false, but R1 is true. 5. T1 reads R1 and doesn't abort the transaction. 6. T1 calls ELIDE_UNLOCK, which reads false from is_lock_free and decides to unlock a lock acquired by T2, leading to undefined behavior. This patch delays the evaluation of is_lock_free to inside a transaction by moving this part of the code to the macro ELIDE_LOCK. [BZ #18743] * sysdeps/powerpc/nptl/elide.h (__elide_lock): Move most of this code to... (ELIDE_LOCK): ...here. (__get_new_count): New function with part of the code from __elide_lock that updates the value of adapt_count after a transaction abort. (__elided_trylock): Moved this code to... (ELIDE_TRYLOCK): ...here. ----------------------------------------------------------------------- Summary of changes: ChangeLog | 12 ++++ NEWS | 14 +++--- sysdeps/powerpc/nptl/elide.h | 115 +++++++++++++++++++++++------------------- 3 files changed, 82 insertions(+), 59 deletions(-)
The patch has just been pushed to master.
This is an automated email from the git hooks/post-receive script. It was generated because a ref change was pushed to the repository containing the project "GNU C Library master sources". The branch, release/2.22/master has been updated via 5b319ce2949cf6fb97862ff81558944f76c704f1 (commit) from 5fb7924cb6cf606ce865122e5bbac9df934db14e (commit) Those revisions listed above that are new to this repository have not appeared on any other notification email; so we list those revisions in full, below. - Log ----------------------------------------------------------------- https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=5b319ce2949cf6fb97862ff81558944f76c704f1 commit 5b319ce2949cf6fb97862ff81558944f76c704f1 Author: Tulio Magno Quites Machado Filho <tuliom@linux.vnet.ibm.com> Date: Wed Jul 22 09:26:02 2015 -0300 PowerPC: Fix a race condition when eliding a lock The previous code used to evaluate the preprocessor token is_lock_free to a variable before starting a transaction. This behavior can cause an error if another thread got the lock (without using a transaction) between the evaluation of the token and the beginning of the transaction. This bug can be triggered with the following order of events: 1. The lock accessed by is_lock_free is free. 2. Thread T1 evaluates is_lock_free and stores into register R1 that the lock is free. 3. Thread T2 acquires the same lock used in is_lock_free. 4. T1 begins the transaction, creating a memory barrier where is_lock_free is false, but R1 is true. 5. T1 reads R1 and doesn't abort the transaction. 6. T1 calls ELIDE_UNLOCK, which reads false from is_lock_free and decides to unlock a lock acquired by T2, leading to undefined behavior. This patch delays the evaluation of is_lock_free to inside a transaction by moving this part of the code to the macro ELIDE_LOCK. [BZ #18743] * sysdeps/powerpc/nptl/elide.h (__elide_lock): Move most of this code to... (ELIDE_LOCK): ...here. (__get_new_count): New function with part of the code from __elide_lock that updates the value of adapt_count after a transaction abort. (__elided_trylock): Moved this code to... (ELIDE_TRYLOCK): ...here. (cherry picked from commit 6ec52bf634b7650b57ff67b5f5053bce8992d549) ----------------------------------------------------------------------- Summary of changes: ChangeLog | 12 ++++ NEWS | 4 +- sysdeps/powerpc/nptl/elide.h | 115 +++++++++++++++++++++++------------------- 3 files changed, 77 insertions(+), 54 deletions(-)
This is an automated email from the git hooks/post-receive script. It was generated because a ref change was pushed to the repository containing the project "GNU C Library master sources". The branch, gentoo/2.22 has been updated via b4f19537f9d26dbf95bd2e7d9c056400ad1b5723 (commit) from 0f74aed2de00dfbcae8e0217d6abdd5634e1c69c (commit) Those revisions listed above that are new to this repository have not appeared on any other notification email; so we list those revisions in full, below. - Log ----------------------------------------------------------------- https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=b4f19537f9d26dbf95bd2e7d9c056400ad1b5723 commit b4f19537f9d26dbf95bd2e7d9c056400ad1b5723 Author: Tulio Magno Quites Machado Filho <tuliom@linux.vnet.ibm.com> Date: Wed Jul 22 09:26:02 2015 -0300 PowerPC: Fix a race condition when eliding a lock The previous code used to evaluate the preprocessor token is_lock_free to a variable before starting a transaction. This behavior can cause an error if another thread got the lock (without using a transaction) between the evaluation of the token and the beginning of the transaction. This bug can be triggered with the following order of events: 1. The lock accessed by is_lock_free is free. 2. Thread T1 evaluates is_lock_free and stores into register R1 that the lock is free. 3. Thread T2 acquires the same lock used in is_lock_free. 4. T1 begins the transaction, creating a memory barrier where is_lock_free is false, but R1 is true. 5. T1 reads R1 and doesn't abort the transaction. 6. T1 calls ELIDE_UNLOCK, which reads false from is_lock_free and decides to unlock a lock acquired by T2, leading to undefined behavior. This patch delays the evaluation of is_lock_free to inside a transaction by moving this part of the code to the macro ELIDE_LOCK. [BZ #18743] * sysdeps/powerpc/nptl/elide.h (__elide_lock): Move most of this code to... (ELIDE_LOCK): ...here. (__get_new_count): New function with part of the code from __elide_lock that updates the value of adapt_count after a transaction abort. (__elided_trylock): Moved this code to... (ELIDE_TRYLOCK): ...here. (cherry picked from commit 6ec52bf634b7650b57ff67b5f5053bce8992d549) (cherry picked from commit 5b319ce2949cf6fb97862ff81558944f76c704f1) ----------------------------------------------------------------------- Summary of changes: sysdeps/powerpc/nptl/elide.h | 115 +++++++++++++++++++++++------------------- 1 files changed, 63 insertions(+), 52 deletions(-)