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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 22:56:36 +1200 |
| commit | 422952ee78220c49812b7697c7855c6230840e35 (patch) | |
| tree | 03b52fbb1c6361b8655afbd7807bcadd2e344535 /src | |
| parent | 1d6fbc38d9ed03dc7fd297119d7949b6531aed5a (diff) | |
| download | postgresql-422952ee78220c49812b7697c7855c6230840e35.tar.gz postgresql-422952ee78220c49812b7697c7855c6230840e35.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')
| -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 77e1bab54be..70f899e7658 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> @@ -330,6 +331,14 @@ 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", @@ -419,11 +428,15 @@ 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 |