[GIT PULL] tracing: Fixes for v6.6-rc3
From: Steven Rostedt
Date: Sat Sep 30 2023 - 16:47:14 EST
Beau Belgrave <beaub@xxxxxxxxxxxxxxxxxxx>, Clément Léger <cleger@xxxxxxxxxxxx>
Linus,
Tracing fixes for v6.6-rc3:
- Make sure 32 bit applications using user events have aligned access when
running on a 64 bit kernel.
- Add cond_resched in the loop that handles converting enums in print_fmt
string is trace events.
- Fix premature wake ups of polling processes in the tracing ring buffer. When
a task polls waiting for a percentage of the ring buffer to be filled, the
writer still will wake it up at every event. Add the polling's percentage to
the "shortest_full" list to tell the writer when to wake it up.
- For eventfs dir lookups on dynamic events, an event system's only event could
be removed, leaving its dentry with no children. This is totally legitimate.
But in eventfs_release() it must not access the children array, as it is only
allocated when the dentry has children.
Please pull the latest trace-v6.6-rc3 tree, which can be found at:
git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace.git
trace-v6.6-rc3
Tag SHA1: 805f65c2b5fbd7357e47a1808fcad8629dda9f07
Head SHA1: 2598bd3ca8dcf5bbca1161ee5b271b432398da37
Beau Belgrave (1):
tracing/user_events: Align set_bit() address for all archs
Clément Léger (1):
tracing: relax trace_event_eval_update() execution with cond_resched()
Steven Rostedt (Google) (2):
ring-buffer: Update "shortest_full" in polling
eventfs: Test for dentries array allocated in eventfs_release()
----
fs/tracefs/event_inode.c | 2 +-
kernel/trace/ring_buffer.c | 3 +++
kernel/trace/trace_events.c | 1 +
kernel/trace/trace_events_user.c | 58 +++++++++++++++++++++++++++++++++++-----
4 files changed, 56 insertions(+), 8 deletions(-)
---------------------------
diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c
index 5f1714089884..8c8d64e76103 100644
--- a/fs/tracefs/event_inode.c
+++ b/fs/tracefs/event_inode.c
@@ -421,7 +421,7 @@ static int eventfs_release(struct inode *inode, struct file *file)
if (WARN_ON_ONCE(!dlist))
return -EINVAL;
- for (i = 0; dlist->dentries[i]; i++) {
+ for (i = 0; dlist->dentries && dlist->dentries[i]; i++) {
dput(dlist->dentries[i]);
}
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 28daf0ce95c5..515cafdb18d9 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -1137,6 +1137,9 @@ __poll_t ring_buffer_poll_wait(struct trace_buffer *buffer, int cpu,
if (full) {
poll_wait(filp, &work->full_waiters, poll_table);
work->full_waiters_pending = true;
+ if (!cpu_buffer->shortest_full ||
+ cpu_buffer->shortest_full > full)
+ cpu_buffer->shortest_full = full;
} else {
poll_wait(filp, &work->waiters, poll_table);
work->waiters_pending = true;
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 91951d038ba4..f49d6ddb6342 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -2770,6 +2770,7 @@ void trace_event_eval_update(struct trace_eval_map **map, int len)
update_event_fields(call, map[i]);
}
}
+ cond_resched();
}
up_write(&trace_event_sem);
}
diff --git a/kernel/trace/trace_events_user.c b/kernel/trace/trace_events_user.c
index 6f046650e527..b87f41187c6a 100644
--- a/kernel/trace/trace_events_user.c
+++ b/kernel/trace/trace_events_user.c
@@ -127,8 +127,13 @@ struct user_event_enabler {
/* Bit 7 is for freeing status of enablement */
#define ENABLE_VAL_FREEING_BIT 7
-/* Only duplicate the bit value */
-#define ENABLE_VAL_DUP_MASK ENABLE_VAL_BIT_MASK
+/* Bit 8 is for marking 32-bit on 64-bit */
+#define ENABLE_VAL_32_ON_64_BIT 8
+
+#define ENABLE_VAL_COMPAT_MASK (1 << ENABLE_VAL_32_ON_64_BIT)
+
+/* Only duplicate the bit and compat values */
+#define ENABLE_VAL_DUP_MASK (ENABLE_VAL_BIT_MASK | ENABLE_VAL_COMPAT_MASK)
#define ENABLE_BITOPS(e) (&(e)->values)
@@ -174,6 +179,30 @@ struct user_event_validator {
int flags;
};
+static inline void align_addr_bit(unsigned long *addr, int *bit,
+ unsigned long *flags)
+{
+ if (IS_ALIGNED(*addr, sizeof(long))) {
+#ifdef __BIG_ENDIAN
+ /* 32 bit on BE 64 bit requires a 32 bit offset when aligned. */
+ if (test_bit(ENABLE_VAL_32_ON_64_BIT, flags))
+ *bit += 32;
+#endif
+ return;
+ }
+
+ *addr = ALIGN_DOWN(*addr, sizeof(long));
+
+ /*
+ * We only support 32 and 64 bit values. The only time we need
+ * to align is a 32 bit value on a 64 bit kernel, which on LE
+ * is always 32 bits, and on BE requires no change when unaligned.
+ */
+#ifdef __LITTLE_ENDIAN
+ *bit += 32;
+#endif
+}
+
typedef void (*user_event_func_t) (struct user_event *user, struct iov_iter *i,
void *tpdata, bool *faulted);
@@ -482,6 +511,7 @@ static int user_event_enabler_write(struct user_event_mm *mm,
unsigned long *ptr;
struct page *page;
void *kaddr;
+ int bit = ENABLE_BIT(enabler);
int ret;
lockdep_assert_held(&event_mutex);
@@ -497,6 +527,8 @@ static int user_event_enabler_write(struct user_event_mm *mm,
test_bit(ENABLE_VAL_FREEING_BIT, ENABLE_BITOPS(enabler))))
return -EBUSY;
+ align_addr_bit(&uaddr, &bit, ENABLE_BITOPS(enabler));
+
ret = pin_user_pages_remote(mm->mm, uaddr, 1, FOLL_WRITE | FOLL_NOFAULT,
&page, NULL);
@@ -515,9 +547,9 @@ static int user_event_enabler_write(struct user_event_mm *mm,
/* Update bit atomically, user tracers must be atomic as well */
if (enabler->event && enabler->event->status)
- set_bit(ENABLE_BIT(enabler), ptr);
+ set_bit(bit, ptr);
else
- clear_bit(ENABLE_BIT(enabler), ptr);
+ clear_bit(bit, ptr);
kunmap_local(kaddr);
unpin_user_pages_dirty_lock(&page, 1, true);
@@ -849,6 +881,12 @@ static struct user_event_enabler
enabler->event = user;
enabler->addr = uaddr;
enabler->values = reg->enable_bit;
+
+#if BITS_PER_LONG >= 64
+ if (reg->enable_size == 4)
+ set_bit(ENABLE_VAL_32_ON_64_BIT, ENABLE_BITOPS(enabler));
+#endif
+
retry:
/* Prevents state changes from racing with new enablers */
mutex_lock(&event_mutex);
@@ -2377,7 +2415,8 @@ static long user_unreg_get(struct user_unreg __user *ureg,
}
static int user_event_mm_clear_bit(struct user_event_mm *user_mm,
- unsigned long uaddr, unsigned char bit)
+ unsigned long uaddr, unsigned char bit,
+ unsigned long flags)
{
struct user_event_enabler enabler;
int result;
@@ -2385,7 +2424,7 @@ static int user_event_mm_clear_bit(struct user_event_mm *user_mm,
memset(&enabler, 0, sizeof(enabler));
enabler.addr = uaddr;
- enabler.values = bit;
+ enabler.values = bit | flags;
retry:
/* Prevents state changes from racing with new enablers */
mutex_lock(&event_mutex);
@@ -2415,6 +2454,7 @@ static long user_events_ioctl_unreg(unsigned long uarg)
struct user_event_mm *mm = current->user_event_mm;
struct user_event_enabler *enabler, *next;
struct user_unreg reg;
+ unsigned long flags;
long ret;
ret = user_unreg_get(ureg, ®);
@@ -2425,6 +2465,7 @@ static long user_events_ioctl_unreg(unsigned long uarg)
if (!mm)
return -ENOENT;
+ flags = 0;
ret = -ENOENT;
/*
@@ -2441,6 +2482,9 @@ static long user_events_ioctl_unreg(unsigned long uarg)
ENABLE_BIT(enabler) == reg.disable_bit) {
set_bit(ENABLE_VAL_FREEING_BIT, ENABLE_BITOPS(enabler));
+ /* We must keep compat flags for the clear */
+ flags |= enabler->values & ENABLE_VAL_COMPAT_MASK;
+
if (!test_bit(ENABLE_VAL_FAULTING_BIT, ENABLE_BITOPS(enabler)))
user_event_enabler_destroy(enabler, true);
@@ -2454,7 +2498,7 @@ static long user_events_ioctl_unreg(unsigned long uarg)
/* Ensure bit is now cleared for user, regardless of event status */
if (!ret)
ret = user_event_mm_clear_bit(mm, reg.disable_addr,
- reg.disable_bit);
+ reg.disable_bit, flags);
return ret;
}