@@ -7,13 +7,14 @@
#include <pthread.h>
#include <sys/epoll.h>
#include <sys/socket.h>
+#include <sys/eventfd.h>
#include "../../kselftest_harness.h"
struct epoll_mtcontext
{
int efd[3];
int sfd[4];
- int count;
+ volatile int count;
pthread_t main;
pthread_t waiter;
@@ -3071,4 +3072,68 @@ TEST(epoll58)
close(ctx.sfd[3]);
}
+static void *epoll59_thread(void *ctx_)
+{
+ struct epoll_mtcontext *ctx = ctx_;
+ struct epoll_event e;
+ int i;
+
+ for (i = 0; i < 100000; i++) {
+ while (ctx->count == 0)
+ ;
+
+ e.events = EPOLLIN | EPOLLERR | EPOLLET;
+ epoll_ctl(ctx->efd[0], EPOLL_CTL_MOD, ctx->sfd[0], &e);
+ ctx->count = 0;
+ }
+
+ return NULL;
+}
+
+/*
+ * t0
+ * (p) \
+ * e0
+ * (et) /
+ * e0
+ *
+ * Based on https://bugzilla.kernel.org/show_bug.cgi?id=205933
+ */
+TEST(epoll59)
+{
+ pthread_t emitter;
+ struct pollfd pfd;
+ struct epoll_event e;
+ struct epoll_mtcontext ctx = { 0 };
+ int i, ret;
+
+ signal(SIGUSR1, signal_handler);
+
+ ctx.efd[0] = epoll_create1(0);
+ ASSERT_GE(ctx.efd[0], 0);
+
+ ctx.sfd[0] = eventfd(1, 0);
+ ASSERT_GE(ctx.sfd[0], 0);
+
+ e.events = EPOLLIN | EPOLLERR | EPOLLET;
+ ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.sfd[0], &e), 0);
+
+ ASSERT_EQ(pthread_create(&emitter, NULL, epoll59_thread, &ctx), 0);
+
+ for (i = 0; i < 100000; i++) {
+ ret = epoll_wait(ctx.efd[0], &e, 1, 1000);
+ ASSERT_GT(ret, 0);
+
+ while (ctx.count != 0)
+ ;
+ ctx.count = 1;
+ }
+ if (pthread_tryjoin_np(emitter, NULL) < 0) {
+ pthread_kill(emitter, SIGUSR1);
+ pthread_join(emitter, NULL);
+ }
+ close(ctx.efd[0]);
+ close(ctx.sfd[0]);
+}
+
TEST_HARNESS_MAIN
This testcase repeats epollbug.c from the bug: https://bugzilla.kernel.org/show_bug.cgi?id=205933 What it tests? It tests the race between epoll_ctl() and epoll_wait(). New event mask passed to epoll_ctl() triggers wake up, which can be missed because of the bug described in the link. Reproduction is 100%, so easy to fix. Kudos, Max, for wonderful test case. Signed-off-by: Roman Penyaev <rpenyaev@suse.de> Cc: Max Neunhoeffer <max@arangodb.com> Cc: Jakub Kicinski <kuba@kernel.org> Cc: Christopher Kohlhoff <chris.kohlhoff@clearpool.io> Cc: Davidlohr Bueso <dbueso@suse.de> Cc: Jason Baron <jbaron@akamai.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: linux-fsdevel@vger.kernel.org Cc: linux-kernel@vger.kernel.org --- Nothing was changed in v3 Nothing interesting in v2: changed the comment a bit .../filesystems/epoll/epoll_wakeup_test.c | 67 ++++++++++++++++++- 1 file changed, 66 insertions(+), 1 deletion(-)