diff options
| -rw-r--r-- | lib/frr_pthread.c | 8 | ||||
| -rw-r--r-- | lib/frrcu.c | 15 | ||||
| -rw-r--r-- | lib/sigevent.h | 27 |
3 files changed, 45 insertions, 5 deletions
diff --git a/lib/frr_pthread.c b/lib/frr_pthread.c index 3a4bc712fc..0b4d7c77ae 100644 --- a/lib/frr_pthread.c +++ b/lib/frr_pthread.c @@ -20,6 +20,7 @@ #include "zlog.h" #include "libfrr.h" #include "libfrr_trace.h" +#include "sigevent.h" DEFINE_MTYPE_STATIC(LIB, FRR_PTHREAD, "FRR POSIX Thread"); DEFINE_MTYPE_STATIC(LIB, PTHREAD_PRIM, "POSIX sync primitives"); @@ -185,10 +186,9 @@ int frr_pthread_run(struct frr_pthread *fpt, const pthread_attr_t *attr) assert(frr_is_after_fork || !"trying to start thread before fork()"); - /* Ensure we never handle signals on a background thread by blocking - * everything here (new thread inherits signal mask) - */ - sigfillset(&blocksigs); + sigemptyset(&blocksigs); + frr_sigset_add_mainonly(&blocksigs); + /* new thread inherits mask */ pthread_sigmask(SIG_BLOCK, &blocksigs, &oldsigs); frrtrace(1, frr_libfrr, frr_pthread_run, fpt->name); diff --git a/lib/frrcu.c b/lib/frrcu.c index b85c525c58..1e7ed99eff 100644 --- a/lib/frrcu.c +++ b/lib/frrcu.c @@ -42,6 +42,7 @@ #include "frrcu.h" #include "seqlock.h" #include "atomlist.h" +#include "sigevent.h" DEFINE_MTYPE_STATIC(LIB, RCU_THREAD, "RCU thread"); DEFINE_MTYPE_STATIC(LIB, RCU_NEXT, "RCU sequence barrier"); @@ -346,7 +347,19 @@ static void rcu_start(void) */ sigset_t oldsigs, blocksigs; - sigfillset(&blocksigs); + /* technically, the RCU thread is very poorly suited to run even just a + * crashlog handler, since zlog_sigsafe() could deadlock on transiently + * invalid (due to RCU) logging data structures + * + * but given that when we try to write a crashlog, we're already in + * b0rked territory anyway - give the crashlog handler a chance. + * + * (also cf. the SIGALRM usage in writing crashlogs to avoid hung + * processes on any kind of deadlock in crash handlers) + */ + sigemptyset(&blocksigs); + frr_sigset_add_mainonly(&blocksigs); + /* new thread inherits mask */ pthread_sigmask(SIG_BLOCK, &blocksigs, &oldsigs); rcu_active = true; diff --git a/lib/sigevent.h b/lib/sigevent.h index 0b07f594c1..2c51ba3767 100644 --- a/lib/sigevent.h +++ b/lib/sigevent.h @@ -45,6 +45,33 @@ bool frr_sigevent_check(sigset_t *setp); /* check whether there are signals to handle, process any found */ extern int frr_sigevent_process(void); +/* Ensure we don't handle "application-type" signals on a secondary thread by + * blocking these signals when creating threads + * + * NB: SIGSEGV, SIGABRT, etc. must be allowed on all threads or we get no + * crashlogs. Since signals vary a little bit between platforms, below is a + * list of known things to go to the main thread. Any unknown signals should + * stay thread-local. + */ +static inline void frr_sigset_add_mainonly(sigset_t *blocksigs) +{ + /* signals we actively handle */ + sigaddset(blocksigs, SIGHUP); + sigaddset(blocksigs, SIGINT); + sigaddset(blocksigs, SIGTERM); + sigaddset(blocksigs, SIGUSR1); + + /* signals we don't actively use but that semantically belong */ + sigaddset(blocksigs, SIGUSR2); + sigaddset(blocksigs, SIGQUIT); + sigaddset(blocksigs, SIGCHLD); + sigaddset(blocksigs, SIGPIPE); + sigaddset(blocksigs, SIGTSTP); + sigaddset(blocksigs, SIGTTIN); + sigaddset(blocksigs, SIGTTOU); + sigaddset(blocksigs, SIGWINCH); +} + #ifdef __cplusplus } #endif |