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authorTavian Barnes <tavianator@tavianator.com>2024-06-07 13:03:34 -0400
committerTavian Barnes <tavianator@tavianator.com>2024-06-07 13:03:34 -0400
commit778295321928767552ebc577f15e88c17da4c1c9 (patch)
tree9ea82f1363921a2c379a3b8ef70ef6c19a74d0cc /src
parenta01cfacd423af28af6b7c13ba51e2395f3a52ee7 (diff)
downloadbfs-778295321928767552ebc577f15e88c17da4c1c9.tar.xz
sighook: Shard the signal table
Diffstat (limited to 'src')
-rw-r--r--src/sighook.c31
1 files changed, 24 insertions, 7 deletions
diff --git a/src/sighook.c b/src/sighook.c
index 1146ea7..6d6ff01 100644
--- a/src/sighook.c
+++ b/src/sighook.c
@@ -327,11 +327,16 @@ static int rcu_sigtable_add(struct rcu *rcu, struct sighook *hook) {
return 0;
}
-/** The global table of signal hooks. */
-static struct rcu rcu_sighooks;
-/** The global table of atsigexit() hooks. */
+/** The sharded table of signal hooks. */
+static struct rcu rcu_sighooks[64];
+/** The table of atsigexit() hooks. */
static struct rcu rcu_exithooks;
+/** Get the table for a particular signal. */
+static struct rcu *sigshard(int sig) {
+ return &rcu_sighooks[sig % countof(rcu_sighooks)];
+}
+
/** Mutex for initialization and RCU writer exclusion. */
static pthread_mutex_t sigmutex = PTHREAD_MUTEX_INITIALIZER;
@@ -479,7 +484,8 @@ static void sigdispatch(int sig, siginfo_t *info, void *context) {
int error = errno;
// Run the normal hooks
- enum sigflags flags = run_hooks(&rcu_sighooks, sig, info);
+ struct rcu *shard = sigshard(sig);
+ enum sigflags flags = run_hooks(shard, sig, info);
// Run the atsigexit() hooks, if we're exiting
if (!(flags & SH_CONTINUE) && is_fatal(sig)) {
@@ -505,8 +511,12 @@ static int siginit(int sig) {
|| sigemptyset(&action.sa_mask) != 0) {
return -1;
}
- rcu_init(&rcu_sighooks);
+
+ for (size_t i = 0; i < countof(rcu_sighooks); ++i) {
+ rcu_init(&rcu_sighooks[i]);
+ }
rcu_init(&rcu_exithooks);
+
initialized = true;
}
@@ -556,7 +566,8 @@ struct sighook *sighook(int sig, sighook_fn *fn, void *arg, enum sigflags flags)
goto done;
}
- ret = sighook_impl(&rcu_sighooks, sig, fn, arg, flags);
+ struct rcu *shard = sigshard(sig);
+ ret = sighook_impl(shard, sig, fn, arg, flags);
done:
mutex_unlock(&sigmutex);
return ret;
@@ -590,7 +601,13 @@ void sigunhook(struct sighook *hook) {
mutex_lock(&sigmutex);
- struct rcu *rcu = hook->sig ? &rcu_sighooks : &rcu_exithooks;
+ struct rcu *rcu;
+ if (hook->sig) {
+ rcu = sigshard(hook->sig);
+ } else {
+ rcu = &rcu_exithooks;
+ }
+
struct sigtable *table = rcu_peek(rcu);
bfs_verify(sigtable_del(table, hook) == 0);