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| author | Florian Weimer <fweimer@redhat.com> | 2016-05-13 16:55:01 +0200 |
|---|---|---|
| committer | Florian Weimer <fweimer@redhat.com> | 2016-05-13 20:43:14 +0200 |
| commit | e2cd73a2ccabe8acae28719a0c3c1c03f2b5f9fb (patch) | |
| tree | aef0595da097dc402f27a64dde84f3713f9ee510 | |
| parent | fdbdbc83a53cfee6edff9f737e188a56925f1db1 (diff) | |
| download | glibc-e2cd73a2ccabe8acae28719a0c3c1c03f2b5f9fb.tar.gz glibc-e2cd73a2ccabe8acae28719a0c3c1c03f2b5f9fb.tar.xz glibc-e2cd73a2ccabe8acae28719a0c3c1c03f2b5f9fb.zip | |
tst-mallocfork2: Fix race condition, use fewer resources
The first SIGUSR1 signal could arrive when sigusr1_sender_pid was still 0. As a result, kill would send SIGSTOP to the entire process group. This would cause the test to hang before printing any output. This commit also adds a sched_yield to the signal source, so that it does not flood the parent process with signals it has never a chance to handle. Even with these changes, tst-mallocfork2 still fails reliably after the fix in commit commit 56290d6e762c1194547e73ff0b948cd79d3a1e03 (Increase fork signal safety for single-threaded processes) is backed out.
| -rw-r--r-- | ChangeLog | 7 | ||||
| -rw-r--r-- | malloc/tst-mallocfork2.c | 8 |
2 files changed, 14 insertions, 1 deletions
diff --git a/ChangeLog b/ChangeLog index 5329849343..a191caff00 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,10 @@ +2016-05-13 Florian Weimer <fweimer@redhat.com> + + Fix race condition in tst-mallocfork2, use fewer resources. + * malloc/tst-mallocfork2.c (sigusr1_handler): Do not send SIGSTOP + to current process group. + (signal_sender): Yield in the non-sleeping case. + 2016-05-13 Joseph Myers <joseph@codesourcery.com> * conform/data/stdlib.h-data (a64l): Do not expect for [XPG3]. diff --git a/malloc/tst-mallocfork2.c b/malloc/tst-mallocfork2.c index a9e3e94aad..4939938a44 100644 --- a/malloc/tst-mallocfork2.c +++ b/malloc/tst-mallocfork2.c @@ -25,6 +25,7 @@ still make fork unsafe, even in single-threaded processes. */ #include <errno.h> +#include <sched.h> #include <signal.h> #include <stdbool.h> #include <stdio.h> @@ -70,7 +71,9 @@ sigusr1_handler (int signo) signals from the subprocess. */ if (sigusr1_received) return; - if (kill (sigusr1_sender_pid, SIGSTOP) != 0) + /* sigusr1_sender_pid might not be initialized in the parent when + the first SIGUSR1 signal arrives. */ + if (sigusr1_sender_pid > 0 && kill (sigusr1_sender_pid, SIGSTOP) != 0) { write_message ("error: kill (SIGSTOP)\n"); abort (); @@ -123,6 +126,9 @@ signal_sender (int signo, bool sleep) } if (sleep) usleep (1 * 1000 * 1000); + else + /* Reduce the rate at which we send signals. */ + sched_yield (); } } |