prevent locking fd table while holding a mutex #90
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uvwasi_path_rename(), uvwasi_path_link(), uvwasi_path_open(), and uvwasi_fd_renumber() operate on multiple file descriptors. uvwasi_fd_renumber() has been updated prior to this commit, and is not relevant here. The other three functions would perform the following locking operations: - lock the file table - acquire a file descriptor mutex - unlock the file table - unlock the file table again - acquire another file descriptor mutex - unlock the file table - unlock the two mutexes Attempting to acquire the second mutex introduced the possibility of deadlock because another thread could attempt to acquire the first mutex while holding the file table lock. This commit ensures that multiple mutexes are either: - acquired in a single lock of the file table - or, only acquired after releasing previously held mutexes Fixes: #89
bnoordhuis
approved these changes
Jan 22, 2020
|
Thanks for pointing these issues out Ben. |
This was referenced Mar 14, 2020
Merged
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uvwasi_path_rename(),uvwasi_path_link(),uvwasi_path_open(), anduvwasi_fd_renumber()operate on multiple file descriptors.uvwasi_fd_renumber()has been updated prior to this commit, and is not relevant here. The other three functions would performthe following locking operations:
Attempting to acquire the second mutex introduced the possibility of deadlock because another thread could attempt to acquire the first mutex while holding the file table lock.
This commit ensures that multiple mutexes are either:
Fixes: #89
Refs: nodejs/node#31432 (comment)