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pid1: make use of high rt signals on hppa with newer kernels 

Back in 4dffec1459 we stopped using SIGRTMIN+26
and higher on hppa because they were not available. Then they became available
in linux 3.18:

  https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=1f25df2eff5b25f52c139d3ff31bc883eee9a0ab

Instead of hard-coding the list based on architecture, let's use a runtime
check like signal(7) says.

(A note about implementation: RTSIG_IF_AVAILABLE is defined to take the full
signal and not just an offset from SIGRTMIN so that it's still possible to
grep for SIGRTMIN\+.)

Add a simple "test" to print the signal values.

Fixes https://bugs.freedesktop.org/show_bug.cgi?id=84931.
This commit is contained in:
Zbigniew Jędrzejewski-Szmek 2018-03-09 09:32:03 +01:00
parent cd001016a1
commit 8750ac0238
2 changed files with 27 additions and 13 deletions
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28
src/core/manager.c
View File

@ -426,6 +426,8 @@ static int enable_special_signals(Manager *m) {
return 0;
}
#define RTSIG_IF_AVAILABLE(signum) (signum <= SIGRTMAX ? signum : -1)
static int manager_setup_signals(Manager *m) {
struct sigaction sa = {
.sa_handler = SIG_DFL,
@ -479,22 +481,22 @@ static int manager_setup_signals(Manager *m) {
/* .. one free signal here ... */
#if !defined(__hppa64__) && !defined(__hppa__)
/* Apparently Linux on hppa has fewer RT
* signals (SIGRTMAX is SIGRTMIN+25 there),
* hence let's not try to make use of them
* here. Since these commands are accessible
* by different means and only really a safety
* net, the missing functionality on hppa
* shouldn't matter. */
/* Apparently Linux on hppa had fewer RT signals until v3.18,
* SIGRTMAX was SIGRTMIN+25, and then SIGRTMIN was lowered,
* see commit v3.17-7614-g1f25df2eff.
*
* We cannot unconditionally make use of those signals here,
* so let's use a runtime check. Since these commands are
* accessible by different means and only really a safety
* net, the missing functionality on hppa shouldn't matter.
*/
SIGRTMIN+26, /* systemd: set log target to journal-or-kmsg */
SIGRTMIN+27, /* systemd: set log target to console */
SIGRTMIN+28, /* systemd: set log target to kmsg */
SIGRTMIN+29, /* systemd: set log target to syslog-or-kmsg (obsolete) */
RTSIG_IF_AVAILABLE(SIGRTMIN+26), /* systemd: set log target to journal-or-kmsg */
RTSIG_IF_AVAILABLE(SIGRTMIN+27), /* systemd: set log target to console */
RTSIG_IF_AVAILABLE(SIGRTMIN+28), /* systemd: set log target to kmsg */
RTSIG_IF_AVAILABLE(SIGRTMIN+29), /* systemd: set log target to syslog-or-kmsg (obsolete) */
/* ... one free signal here SIGRTMIN+30 ... */
#endif
-1);
assert_se(sigprocmask(SIG_SETMASK, &mask, NULL) == 0);

12
src/test/test-signal-util.c
View File

@ -21,10 +21,21 @@
#include <signal.h>
#include <unistd.h>
#include "log.h"
#include "macro.h"
#include "signal-util.h"
#include "process-util.h"
#define info(sig) log_info(#sig " = " STRINGIFY(sig) " = %d", sig)
static void test_rt_signals(void) {
info(SIGRTMIN);
info(SIGRTMAX);
/* We use signals SIGRTMIN+0 to SIGRTMIN+24 unconditionally */
assert(SIGRTMAX - SIGRTMIN >= 24);
}
static void test_block_signals(void) {
sigset_t ss;
@ -62,6 +73,7 @@ static void test_ignore_signals(void) {
}
int main(int argc, char *argv[]) {
test_rt_signals();
test_block_signals();
test_ignore_signals();