path: root/src/thread/x86_64/__unmapself.s
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authorRich Felker <>2011-06-14 01:35:51 -0400
committerRich Felker <>2011-06-14 01:35:51 -0400
commit7779dbd2663269b465951189b4f43e70839bc073 (patch)
treefa131e2ddcf164bf4d58a07f627a4704a0b13f73 /src/thread/x86_64/__unmapself.s
parentf58c8a0f391987a65e055ae591ec59b9df7b7f7c (diff)
fix race condition in pthread_kill
if thread id was reused by the kernel between the time pthread_kill read it from the userspace pthread_t object and the time of the tgkill syscall, a signal could be sent to the wrong thread. the tgkill syscall was supposed to prevent this race (versus the old tkill syscall) but it can't; it can only help in the case where the tid is reused in a different process, but not when the tid is reused in the same process. the only solution i can see is an extra lock to prevent threads from exiting while another thread is trying to pthread_kill them. it should be very very cheap in the non-contended case.
Diffstat (limited to 'src/thread/x86_64/__unmapself.s')
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