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| author | Thomas Munro <tmunro@postgresql.org> | 2018-09-18 22:56:36 +1200 |
|---|---|---|
| committer | Thomas Munro <tmunro@postgresql.org> | 2018-09-18 23:03:54 +1200 |
| commit | 63efab4ca139ab18095b8e095d5708d5566fc9e2 (patch) | |
| tree | 8fe28b28953b90d9a38162a7e3581f6762bf24de /src/backend | |
| parent | 3d65e406d1ea82060ad13a7bc41178ed22c599d1 (diff) | |
| download | postgresql-63efab4ca139ab18095b8e095d5708d5566fc9e2.tar.gz postgresql-63efab4ca139ab18095b8e095d5708d5566fc9e2.zip | |
Allow DSM allocation to be interrupted.
Chris Travers reported that the startup process can repeatedly try to
cancel a backend that is in a posix_fallocate()/EINTR loop and cause it
to loop forever. Teach the retry loop to give up if an interrupt is
pending. Don't actually check for interrupts in that loop though,
because a non-local exit would skip some clean-up code in the caller.
Back-patch to 9.4 where DSM was added (and posix_fallocate() was later
back-patched).
Author: Chris Travers
Reviewed-by: Ildar Musin, Murat Kabilov, Oleksii Kliukin
Tested-by: Oleksii Kliukin
Discussion: https://postgr.es/m/CAN-RpxB-oeZve_J3SM_6%3DHXPmvEG%3DHX%2B9V9pi8g2YR7YW0rBBg%40mail.gmail.com
Diffstat (limited to 'src/backend')
| -rw-r--r-- | src/backend/storage/ipc/dsm_impl.c | 17 |
1 files changed, 15 insertions, 2 deletions
diff --git a/src/backend/storage/ipc/dsm_impl.c b/src/backend/storage/ipc/dsm_impl.c index c6382ec031b..b79701d8375 100644 --- a/src/backend/storage/ipc/dsm_impl.c +++ b/src/backend/storage/ipc/dsm_impl.c @@ -47,6 +47,7 @@ */ #include "postgres.h" +#include "miscadmin.h" #include <fcntl.h> #include <unistd.h> @@ -333,6 +334,14 @@ dsm_impl_posix(dsm_op op, dsm_handle handle, Size request_size, shm_unlink(name); errno = save_errno; + /* + * If we received a query cancel or termination signal, we will have + * EINTR set here. If the caller said that errors are OK here, check + * for interrupts immediately. + */ + if (errno == EINTR && elevel >= ERROR) + CHECK_FOR_INTERRUPTS(); + ereport(elevel, (errcode_for_dynamic_shared_memory(), errmsg("could not resize shared memory segment \"%s\" to %zu bytes: %m", @@ -422,11 +431,15 @@ dsm_impl_posix_resize(int fd, off_t size) #if defined(HAVE_POSIX_FALLOCATE) && defined(__linux__) if (rc == 0) { - /* We may get interrupted, if so just retry. */ + /* + * We may get interrupted. If so, just retry unless there is an + * interrupt pending. This avoids the possibility of looping forever + * if another backend is repeatedly trying to interrupt us. + */ do { rc = posix_fallocate(fd, 0, size); - } while (rc == EINTR); + } while (rc == EINTR && !(ProcDiePending || QueryCancelPending)); /* * The caller expects errno to be set, but posix_fallocate() doesn't |