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authorJakub Kicinski <kuba@kernel.org>2022-07-21 13:03:39 -0700
committerJakub Kicinski <kuba@kernel.org>2022-07-21 13:03:39 -0700
commit6e0e846ee2ab01bc44254e6a0a6a6a0db1cba16d (patch)
treee2a39b9ff9fbfa9adbaa004e3b42047664a8e57d /kernel
parent5588d628027092e66195097bdf6835ddf64418b3 (diff)
parent7ca433dc6dedb2ec98dfc943f6db0c9b8996ed11 (diff)
downloadlinux-6e0e846ee2ab01bc44254e6a0a6a6a0db1cba16d.tar.bz2
Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
No conflicts. Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/events/core.c45
-rw-r--r--kernel/printk/printk.c13
-rw-r--r--kernel/sysctl.c20
-rw-r--r--kernel/watch_queue.c53
4 files changed, 90 insertions, 41 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 48bae58d240e..07d51f95d6a6 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -6253,10 +6253,10 @@ again:
if (!atomic_inc_not_zero(&event->rb->mmap_count)) {
/*
- * Raced against perf_mmap_close() through
- * perf_event_set_output(). Try again, hope for better
- * luck.
+ * Raced against perf_mmap_close(); remove the
+ * event and try again.
*/
+ ring_buffer_attach(event, NULL);
mutex_unlock(&event->mmap_mutex);
goto again;
}
@@ -11829,14 +11829,25 @@ err_size:
goto out;
}
+static void mutex_lock_double(struct mutex *a, struct mutex *b)
+{
+ if (b < a)
+ swap(a, b);
+
+ mutex_lock(a);
+ mutex_lock_nested(b, SINGLE_DEPTH_NESTING);
+}
+
static int
perf_event_set_output(struct perf_event *event, struct perf_event *output_event)
{
struct perf_buffer *rb = NULL;
int ret = -EINVAL;
- if (!output_event)
+ if (!output_event) {
+ mutex_lock(&event->mmap_mutex);
goto set;
+ }
/* don't allow circular references */
if (event == output_event)
@@ -11874,8 +11885,15 @@ perf_event_set_output(struct perf_event *event, struct perf_event *output_event)
event->pmu != output_event->pmu)
goto out;
+ /*
+ * Hold both mmap_mutex to serialize against perf_mmap_close(). Since
+ * output_event is already on rb->event_list, and the list iteration
+ * restarts after every removal, it is guaranteed this new event is
+ * observed *OR* if output_event is already removed, it's guaranteed we
+ * observe !rb->mmap_count.
+ */
+ mutex_lock_double(&event->mmap_mutex, &output_event->mmap_mutex);
set:
- mutex_lock(&event->mmap_mutex);
/* Can't redirect output if we've got an active mmap() */
if (atomic_read(&event->mmap_count))
goto unlock;
@@ -11885,6 +11903,12 @@ set:
rb = ring_buffer_get(output_event);
if (!rb)
goto unlock;
+
+ /* did we race against perf_mmap_close() */
+ if (!atomic_read(&rb->mmap_count)) {
+ ring_buffer_put(rb);
+ goto unlock;
+ }
}
ring_buffer_attach(event, rb);
@@ -11892,20 +11916,13 @@ set:
ret = 0;
unlock:
mutex_unlock(&event->mmap_mutex);
+ if (output_event)
+ mutex_unlock(&output_event->mmap_mutex);
out:
return ret;
}
-static void mutex_lock_double(struct mutex *a, struct mutex *b)
-{
- if (b < a)
- swap(a, b);
-
- mutex_lock(a);
- mutex_lock_nested(b, SINGLE_DEPTH_NESTING);
-}
-
static int perf_event_set_clock(struct perf_event *event, clockid_t clk_id)
{
bool nmi_safe = false;
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index b49c6ff6dca0..a1a81fd9889b 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -3380,6 +3380,7 @@ static bool __pr_flush(struct console *con, int timeout_ms, bool reset_on_progre
diff = 0;
console_lock();
+
for_each_console(c) {
if (con && con != c)
continue;
@@ -3389,11 +3390,19 @@ static bool __pr_flush(struct console *con, int timeout_ms, bool reset_on_progre
if (printk_seq < seq)
diff += seq - printk_seq;
}
- console_unlock();
- if (diff != last_diff && reset_on_progress)
+ /*
+ * If consoles are suspended, it cannot be expected that they
+ * make forward progress, so timeout immediately. @diff is
+ * still used to return a valid flush status.
+ */
+ if (console_suspended)
+ remaining = 0;
+ else if (diff != last_diff && reset_on_progress)
remaining = timeout_ms;
+ console_unlock();
+
if (diff == 0 || remaining == 0)
break;
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 619b02443522..b233714a1c78 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -2135,6 +2135,17 @@ static struct ctl_table vm_table[] = {
.extra1 = SYSCTL_ZERO,
.extra2 = SYSCTL_TWO_HUNDRED,
},
+#ifdef CONFIG_NUMA
+ {
+ .procname = "numa_stat",
+ .data = &sysctl_vm_numa_stat,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = sysctl_vm_numa_stat_handler,
+ .extra1 = SYSCTL_ZERO,
+ .extra2 = SYSCTL_ONE,
+ },
+#endif
#ifdef CONFIG_HUGETLB_PAGE
{
.procname = "nr_hugepages",
@@ -2151,15 +2162,6 @@ static struct ctl_table vm_table[] = {
.mode = 0644,
.proc_handler = &hugetlb_mempolicy_sysctl_handler,
},
- {
- .procname = "numa_stat",
- .data = &sysctl_vm_numa_stat,
- .maxlen = sizeof(int),
- .mode = 0644,
- .proc_handler = sysctl_vm_numa_stat_handler,
- .extra1 = SYSCTL_ZERO,
- .extra2 = SYSCTL_ONE,
- },
#endif
{
.procname = "hugetlb_shm_group",
diff --git a/kernel/watch_queue.c b/kernel/watch_queue.c
index 230038d4f908..bb9962b33f95 100644
--- a/kernel/watch_queue.c
+++ b/kernel/watch_queue.c
@@ -34,6 +34,27 @@ MODULE_LICENSE("GPL");
#define WATCH_QUEUE_NOTE_SIZE 128
#define WATCH_QUEUE_NOTES_PER_PAGE (PAGE_SIZE / WATCH_QUEUE_NOTE_SIZE)
+/*
+ * This must be called under the RCU read-lock, which makes
+ * sure that the wqueue still exists. It can then take the lock,
+ * and check that the wqueue hasn't been destroyed, which in
+ * turn makes sure that the notification pipe still exists.
+ */
+static inline bool lock_wqueue(struct watch_queue *wqueue)
+{
+ spin_lock_bh(&wqueue->lock);
+ if (unlikely(wqueue->defunct)) {
+ spin_unlock_bh(&wqueue->lock);
+ return false;
+ }
+ return true;
+}
+
+static inline void unlock_wqueue(struct watch_queue *wqueue)
+{
+ spin_unlock_bh(&wqueue->lock);
+}
+
static void watch_queue_pipe_buf_release(struct pipe_inode_info *pipe,
struct pipe_buffer *buf)
{
@@ -69,6 +90,10 @@ static const struct pipe_buf_operations watch_queue_pipe_buf_ops = {
/*
* Post a notification to a watch queue.
+ *
+ * Must be called with the RCU lock for reading, and the
+ * watch_queue lock held, which guarantees that the pipe
+ * hasn't been released.
*/
static bool post_one_notification(struct watch_queue *wqueue,
struct watch_notification *n)
@@ -85,9 +110,6 @@ static bool post_one_notification(struct watch_queue *wqueue,
spin_lock_irq(&pipe->rd_wait.lock);
- if (wqueue->defunct)
- goto out;
-
mask = pipe->ring_size - 1;
head = pipe->head;
tail = pipe->tail;
@@ -203,7 +225,10 @@ void __post_watch_notification(struct watch_list *wlist,
if (security_post_notification(watch->cred, cred, n) < 0)
continue;
- post_one_notification(wqueue, n);
+ if (lock_wqueue(wqueue)) {
+ post_one_notification(wqueue, n);
+ unlock_wqueue(wqueue);
+ }
}
rcu_read_unlock();
@@ -462,11 +487,12 @@ int add_watch_to_object(struct watch *watch, struct watch_list *wlist)
return -EAGAIN;
}
- spin_lock_bh(&wqueue->lock);
- kref_get(&wqueue->usage);
- kref_get(&watch->usage);
- hlist_add_head(&watch->queue_node, &wqueue->watches);
- spin_unlock_bh(&wqueue->lock);
+ if (lock_wqueue(wqueue)) {
+ kref_get(&wqueue->usage);
+ kref_get(&watch->usage);
+ hlist_add_head(&watch->queue_node, &wqueue->watches);
+ unlock_wqueue(wqueue);
+ }
hlist_add_head(&watch->list_node, &wlist->watchers);
return 0;
@@ -520,20 +546,15 @@ found:
wqueue = rcu_dereference(watch->queue);
- /* We don't need the watch list lock for the next bit as RCU is
- * protecting *wqueue from deallocation.
- */
- if (wqueue) {
+ if (lock_wqueue(wqueue)) {
post_one_notification(wqueue, &n.watch);
- spin_lock_bh(&wqueue->lock);
-
if (!hlist_unhashed(&watch->queue_node)) {
hlist_del_init_rcu(&watch->queue_node);
put_watch(watch);
}
- spin_unlock_bh(&wqueue->lock);
+ unlock_wqueue(wqueue);
}
if (wlist->release_watch) {