{"push_id":2920059000,"size":2,"distinct_size":2,"ref":"refs/heads/_2_2__core_lock_dont_set_bust_locks_on_lock_error_mbox_master","head":"251aceecd9dc6275a127dc609b67c57c12b8766b","before":"c43c496873876d69cdd38717ed81626fdacb3dda","commits":[{"sha":"7defb44d2f264d8083e7e4d4b7edba18dd9dfa9d","author":{"name":"Nicholas Piggin","email":"24829078df5003d9dd1dd871ca2aeb0b1cf95ef4@gmail.com"},"message":"core/lock: fix timeout warning causing a deadlock false positive\n\nIf a lock waiter exceeds the warning timeout, it prints a message\nwhile still registered as requesting the lock. Printing the message\ncan take locks, so if one is held when the owner of the original\nlock tries to print a message, it will get a false positive deadlock\ndetection, which brings down the system.\n\nThis can easily be hit when there is a lot of HMI activity from a\nKVM guest, where the timebase was not returned to host timebase\nbefore calling the HMI handler.\n\nSigned-off-by: Nicholas Piggin <npiggin@gmail.com>","distinct":true,"url":"https://api.github.com/repos/ruscur/skiboot/commits/7defb44d2f264d8083e7e4d4b7edba18dd9dfa9d"},{"sha":"251aceecd9dc6275a127dc609b67c57c12b8766b","author":{"name":"Nicholas Piggin","email":"24829078df5003d9dd1dd871ca2aeb0b1cf95ef4@gmail.com"},"message":"core/lock: don't set bust_locks on lock error\n\nbust_locks is a big hammer that guarantees a mess if it's set while\nall other threads are not stopped.\n\nI propose removing this in the lock error paths. In debugging the\nprevious deadlock false positive, none of the error messages printed,\nand the in-memory console was totally garbled due to lack of locking.\n\nI think it's generally better for debugging and system integrity to\nkeep locks held when lock errors occur. Lock busting should be used\ncarefully, just to allow messages to be printed out or machine to be\nrestarted, probably when the whole system is single-threaded.\n\nSkiboot is slowly working toward that being feasible with co-operative\ndebug APIs between firmware and host, but for the time being,\ndifficult lock crashes are better not to corrupt everything by\nbusting locks.\n\nSigned-off-by: Nicholas Piggin <npiggin@gmail.com>","distinct":true,"url":"https://api.github.com/repos/ruscur/skiboot/commits/251aceecd9dc6275a127dc609b67c57c12b8766b"}]}
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