deps: update to uvwasi 0.0.5 #31432

cjihrig · 2020-01-20T23:32:47Z

This update improves file descriptor renumbering, and as a result fixes uvwasi_fd_renumber() (which was broken on FreeBSD). Missing uvwasi_fd_renumber() test coverage is also added via an freopen() test.

Checklist

make -j4 test (UNIX), or vcbuild test (Windows) passes
tests and/or benchmarks are included
commit message follows commit guidelines

bnoordhuis · 2020-01-21T09:08:42Z

deps/uvwasi/src/fd_table.c

+  uv_fs_req_cleanup(&req);
+  if (r != 0) {
+    uv_mutex_unlock(&dst_entry->mutex);
+    uv_mutex_unlock(&src_entry->mutex);


These unlocks and the ones at lines 383-384 look like a potential deadlock. You should normally release mutexes in reverse order of acquiring them.

Even when there's no deadlock it's probably still bad for performance because the acquirer can get rescheduled twice in case of contention.

bnoordhuis · 2020-01-21T09:12:38Z

deps/uvwasi/src/fd_table.c

+  /* Move the source entry to the destination slot in the table. */
+  table->fds[dst] = table->fds[src];
+  table->fds[dst]->id = dst;
+  uv_mutex_unlock(&table->fds[dst]->mutex);


I'm also not 100% sure it's safe for this mutex's critical section and &table->rwlock to overlap (but it might be - I just can't tell from the diff. :-))

This version improves file descriptor renumbering, and as a result fixes uvwasi_fd_renumber().

Original commit message: unlock all fd mutexes in reverse order Some functions acquire mutexes for multiple file descriptors. This commit ensures that the mutexes are released in the reverse order that they are aquired.

Original commit message: prevent locking fd table while holding a mutex 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: nodejs/uvwasi#89

Original commit message: prevent race conditions with uvwasi_fd_close() uvwasi_fd_close() performed the following operations: - lock the file descriptor mutex - close the file - release the file descriptor mutex - call the file table's remove() function Once the fd's mutex is released, another thread could acquire it before the fd is removed from the file table. If this happens, remove() could destroy a held mutex. This commit updates uvwasi_fd_close() to perform the entire sequence while holding the file table's lock, preventing new acquisitions of the fd's mutex. Fixes: nodejs/uvwasi#88

This test provides missing coverage for __wasi_fd_renumber().

nodejs-github-bot · 2020-01-23T08:03:09Z

CI: https://ci.nodejs.org/job/node-test-pull-request/28588/ ✔️

Trott · 2020-01-23T13:23:12Z

Landed in c692568...96058f3

This version improves file descriptor renumbering, and as a result fixes uvwasi_fd_renumber(). PR-URL: nodejs#31432 Reviewed-By: Tobias Nießen <tniessen@tnie.de> Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl> Reviewed-By: David Carlier <devnexen@gmail.com> Reviewed-By: Rich Trott <rtrott@gmail.com> Reviewed-By: Jiawen Geng <technicalcute@gmail.com>

Original commit message: unlock all fd mutexes in reverse order Some functions acquire mutexes for multiple file descriptors. This commit ensures that the mutexes are released in the reverse order that they are aquired. PR-URL: nodejs#31432 Reviewed-By: Tobias Nießen <tniessen@tnie.de> Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl> Reviewed-By: David Carlier <devnexen@gmail.com> Reviewed-By: Rich Trott <rtrott@gmail.com> Reviewed-By: Jiawen Geng <technicalcute@gmail.com>

Original commit message: prevent locking fd table while holding a mutex 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: nodejs/uvwasi#89 PR-URL: nodejs#31432 Reviewed-By: Tobias Nießen <tniessen@tnie.de> Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl> Reviewed-By: David Carlier <devnexen@gmail.com> Reviewed-By: Rich Trott <rtrott@gmail.com> Reviewed-By: Jiawen Geng <technicalcute@gmail.com>

Original commit message: prevent race conditions with uvwasi_fd_close() uvwasi_fd_close() performed the following operations: - lock the file descriptor mutex - close the file - release the file descriptor mutex - call the file table's remove() function Once the fd's mutex is released, another thread could acquire it before the fd is removed from the file table. If this happens, remove() could destroy a held mutex. This commit updates uvwasi_fd_close() to perform the entire sequence while holding the file table's lock, preventing new acquisitions of the fd's mutex. Fixes: nodejs/uvwasi#88 PR-URL: #31432 Reviewed-By: Tobias Nießen <tniessen@tnie.de> Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl> Reviewed-By: David Carlier <devnexen@gmail.com> Reviewed-By: Rich Trott <rtrott@gmail.com> Reviewed-By: Jiawen Geng <technicalcute@gmail.com>

This test provides missing coverage for __wasi_fd_renumber(). PR-URL: nodejs#31432 Reviewed-By: Tobias Nießen <tniessen@tnie.de> Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl> Reviewed-By: David Carlier <devnexen@gmail.com> Reviewed-By: Rich Trott <rtrott@gmail.com> Reviewed-By: Jiawen Geng <technicalcute@gmail.com>

This version improves file descriptor renumbering, and as a result fixes uvwasi_fd_renumber(). PR-URL: #31432 Reviewed-By: Tobias Nießen <tniessen@tnie.de> Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl> Reviewed-By: David Carlier <devnexen@gmail.com> Reviewed-By: Rich Trott <rtrott@gmail.com> Reviewed-By: Jiawen Geng <technicalcute@gmail.com>

Original commit message: unlock all fd mutexes in reverse order Some functions acquire mutexes for multiple file descriptors. This commit ensures that the mutexes are released in the reverse order that they are aquired. PR-URL: #31432 Reviewed-By: Tobias Nießen <tniessen@tnie.de> Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl> Reviewed-By: David Carlier <devnexen@gmail.com> Reviewed-By: Rich Trott <rtrott@gmail.com> Reviewed-By: Jiawen Geng <technicalcute@gmail.com>

Original commit message: prevent locking fd table while holding a mutex 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: nodejs/uvwasi#89 PR-URL: #31432 Reviewed-By: Tobias Nießen <tniessen@tnie.de> Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl> Reviewed-By: David Carlier <devnexen@gmail.com> Reviewed-By: Rich Trott <rtrott@gmail.com> Reviewed-By: Jiawen Geng <technicalcute@gmail.com>

Original commit message: prevent race conditions with uvwasi_fd_close() uvwasi_fd_close() performed the following operations: - lock the file descriptor mutex - close the file - release the file descriptor mutex - call the file table's remove() function Once the fd's mutex is released, another thread could acquire it before the fd is removed from the file table. If this happens, remove() could destroy a held mutex. This commit updates uvwasi_fd_close() to perform the entire sequence while holding the file table's lock, preventing new acquisitions of the fd's mutex. Fixes: nodejs/uvwasi#88 PR-URL: #31432 Reviewed-By: Tobias Nießen <tniessen@tnie.de> Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl> Reviewed-By: David Carlier <devnexen@gmail.com> Reviewed-By: Rich Trott <rtrott@gmail.com> Reviewed-By: Jiawen Geng <technicalcute@gmail.com>

This test provides missing coverage for __wasi_fd_renumber(). PR-URL: #31432 Reviewed-By: Tobias Nießen <tniessen@tnie.de> Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl> Reviewed-By: David Carlier <devnexen@gmail.com> Reviewed-By: Rich Trott <rtrott@gmail.com> Reviewed-By: Jiawen Geng <technicalcute@gmail.com>