Mailing List Archive

commit f8936e78a50153f3203bb077be8a067eac0c9663
Author: Poul-Henning Kamp <phk@FreeBSD.org>
Date: Mon Dec 4 08:53:22 2023 +0000

Change the panic reentrancy check so that Coverity can (hopefully) grok it.

diff --git a/bin/varnishd/cache/cache_main.c b/bin/varnishd/cache/cache_main.c
index 3e093c50b..7b433c596 100644
--- a/bin/varnishd/cache/cache_main.c
+++ b/bin/varnishd/cache/cache_main.c
@@ -81,6 +81,7 @@ static pthread_key_t req_key;
static pthread_key_t bo_key;
static pthread_key_t wrk_key;
pthread_key_t witness_key;
+pthread_key_t panic_key;

void
THR_SetBusyobj(const struct busyobj *bo)
@@ -404,6 +405,7 @@ child_main(int sigmagic, size_t altstksz)
PTOK(pthread_key_create(&wrk_key, NULL));
PTOK(pthread_key_create(&witness_key, free));
PTOK(pthread_key_create(&name_key, NULL));
+ PTOK(pthread_key_create(&panic_key, NULL));

THR_SetName("cache-main");

diff --git a/bin/varnishd/cache/cache_panic.c b/bin/varnishd/cache/cache_panic.c
index 221d9835c..eca20c32b 100644
--- a/bin/varnishd/cache/cache_panic.c
+++ b/bin/varnishd/cache/cache_panic.c
@@ -67,7 +67,6 @@

static struct vsb pan_vsb_storage, *pan_vsb;
static pthread_mutex_t panicstr_mtx;
-static pthread_t panicy;

static void pan_sess(struct vsb *, const struct sess *);
static void pan_req(struct vsb *, const struct req *);
@@ -744,18 +743,23 @@ pan_ic(const char *func, const char *file, int line, const char *cond,
struct busyobj *bo;
struct worker *wrk;
struct sigaction sa;
- int err = errno;
+ int i, err = errno;

- /* If we already panicing in another thread, do nothing */
- while (heritage.panic_str[0] && panicy != pthread_self())
- sleep(1);
-
- if (pthread_mutex_lock(&panicstr_mtx)) {
- /* Reentrant panic */
+ if (pthread_getspecific(panic_key) != NULL) {
VSB_cat(pan_vsb, "\n\nPANIC REENTRANCY\n\n");
abort();
}
- panicy = pthread_self();
+
+ /* If we already panicing in another thread, do nothing */
+ do {
+ i = pthread_mutex_trylock(&panicstr_mtx);
+ if (i != 0)
+ sleep (1);
+ } while (i != 0);
+
+ assert (VSB_len(pan_vsb) == 0);
+
+ AZ(pthread_setspecific(panic_key, pan_vsb));

/*
* should we trigger a SIGSEGV while handling a panic, our sigsegv
@@ -844,6 +848,14 @@ pan_ic(const char *func, const char *file, int line, const char *cond,
VSB_putc(pan_vsb, '\0'); /* NUL termination */

v_gcov_flush();
+
+ /*
+ * Do a little song and dance for static checkers which
+ * are not smart enough to figure out that calling abort()
+ * with a mutex held is OK and probably very intentional.
+ */
+ if (pthread_getspecific(panic_key)) /* ie: always */
+ abort();
PTOK(pthread_mutex_unlock(&panicstr_mtx));
abort();
}
diff --git a/bin/varnishd/cache/cache_varnishd.h b/bin/varnishd/cache/cache_varnishd.h
index b534eb174..e9ffad17c 100644
--- a/bin/varnishd/cache/cache_varnishd.h
+++ b/bin/varnishd/cache/cache_varnishd.h
@@ -303,6 +303,7 @@ unsigned HTTP1_Write(const struct worker *w, const struct http *hp, const int*);

/* cache_main.c */
vxid_t VXID_Get(const struct worker *, uint64_t marker);
+extern pthread_key_t panic_key;
extern pthread_key_t witness_key;

void THR_SetName(const char *name);
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