No functional changes, new apis will be used in later patches to
calculate wait time for throttled bios when new configuration is
submitted.

Noted this patch also rename tg_with_in_iops/bps_limit() to
tg_within_iops/bps_limit().

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220829022240.3348319-4-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

There is a problem found by code review in tg_with_in_bps_limit() that
'bps_limit * jiffy_elapsed_rnd' might overflow. Fix the problem by
calling mul_u64_u64_div_u64() instead.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220829022240.3348319-3-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Test scripts:
cd /sys/fs/cgroup/blkio/
echo "8:0 1024" > blkio.throttle.write_bps_device
echo $$ > cgroup.procs
dd if=/dev/zero of=/dev/sda bs=10k count=1 oflag=direct &
dd if=/dev/zero of=/dev/sda bs=10k count=1 oflag=direct &

Test result:
10240 bytes (10 kB, 10 KiB) copied, 10.0134 s, 1.0 kB/s
10240 bytes (10 kB, 10 KiB) copied, 10.0135 s, 1.0 kB/s

The problem is that the second bio is finished after 10s instead of 20s.

Root cause:
1) second bio will be flagged:

__blk_throtl_bio
 while (true) {
  ...
  if (sq->nr_queued[rw]) -> some bio is throttled already
   break
 };
 bio_set_flag(bio, BIO_THROTTLED); -> flag the bio

2) flagged bio will be dispatched without waiting:

throtl_dispatch_tg
 tg_may_dispatch
  tg_with_in_bps_limit
   if (bps_limit == U64_MAX || bio_flagged(bio, BIO_THROTTLED))
    *wait = 0; -> wait time is zero
    return true;

commit 9f5ede3c ("block: throttle split bio in case of iops limit")
support to count split bios for iops limit, thus it adds flagged bio
checking in tg_with_in_bps_limit() so that split bios will only count
once for bps limit, however, it introduce a new problem that io throttle
won't work if multiple bios are throttled.

In order to fix the problem, handle iops/bps limit in different ways:

1) for iops limit, there is no flag to record if the bio is throttled,
   and iops is always applied.
2) for bps limit, original bio will be flagged with BIO_BPS_THROTTLED,
   and io throttle will ignore bio with the flag.

Noted this patch also remove the code to set flag in __bio_clone(), it's
introduced in commit 111be883 ("block-throttle: avoid double
charge"), and author thinks split bio can be resubmited and throttled
again, which is wrong because split bio will continue to dispatch from
caller.

Fixes: 9f5ede3c

 ("block: throttle split bio in case of iops limit")
Cc: <stable@vger.kernel.org>
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220829022240.3348319-2-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Batched completions can clear multiple bits, but we're only decrementing
the wait_cnt by one each time. This can cause waiters to never be woken,
stalling IO. Use the batched count instead.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=215679
Signed-off-by: Keith Busch <kbusch@kernel.org>
Link: https://lore.kernel.org/r/20220909184022.1709476-1-kbusch@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Use atomic_long_try_cmpxchg instead of
atomic_long_cmpxchg (*ptr, old, new) == old in __sbitmap_queue_get_batch.
x86 CMPXCHG instruction returns success in ZF flag, so this change
saves a compare after cmpxchg (and related move instruction in front
of cmpxchg).

Also, atomic_long_cmpxchg implicitly assigns old *ptr value to "old"
when cmpxchg fails, enabling further code simplifications, e.g.
an extra memory read can be avoided in the loop.

No functional change intended.

Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Link: https://lore.kernel.org/r/20220908151200.9993-1-ubizjak@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

syzbot reported hung task [1].  The following program is a simplified
version of the reproducer:

int main(void)
{
	int sv[2], fd;

	if (socketpair(AF_UNIX, SOCK_STREAM, 0, sv) < 0)
		return 1;
	if ((fd = open("/dev/nbd0", 0)) < 0)
		return 1;
	if (ioctl(fd, NBD_SET_SIZE_BLOCKS, 0x81) < 0)
		return 1;
	if (ioctl(fd, NBD_SET_SOCK, sv[0]) < 0)
		return 1;
	if (ioctl(fd, NBD_DO_IT) < 0)
		return 1;
	return 0;
}

When signal interrupt nbd_start_device_ioctl() waiting the condition
atomic_read(&config->recv_threads) == 0, the task can hung because it
waits the completion of the inflight IOs.

This patch fixes the issue by clearing queue, not just shutdown, when
signal interrupt nbd_start_device_ioctl().

Link: https://syzkaller.appspot.com/bug?id=7d89a3ffacd2b83fdd39549bc4d8e0a89ef21239 [1]
Reported-by:  <syzbot+38e6c55d4969a14c1534@syzkaller.appspotmail.com>
Signed-off-by: Shigeru Yoshida <syoshida@redhat.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Link: https://lore.kernel.org/r/20220907163502.577561-1-syoshida@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

When __sbq_wake_up() decrements wait_cnt to 0 but races with someone
else waking the waiter on the waitqueue (so the waitqueue becomes
empty), it exits without reseting wait_cnt to wake_batch number. Once
wait_cnt is 0, nobody will ever reset the wait_cnt or wake the new
waiters resulting in possible deadlocks or busyloops. Fix the problem by
making sure we reset wait_cnt even if we didn't wake up anybody in the
end.

Fixes: 040b83fc

 ("sbitmap: fix possible io hung due to lost wakeup")
Reported-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20220908130937.2795-1-jack@suse.cz
Signed-off-by: Jens Axboe <axboe@kernel.dk>

It is not necessary since it is set later just before function
return success.

Signed-off-by: Guoqing Jiang <guoqing.jiang@linux.dev>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Acked-by: Md Haris Iqbal <haris.iqbal@ionos.com>
Link: https://lore.kernel.org/r/20220902100055.25724-4-guoqing.jiang@linux.dev
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Change the return type to void given it always returns 0.

Signed-off-by: Guoqing Jiang <guoqing.jiang@linux.dev>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Acked-by: Md Haris Iqbal <haris.iqbal@ionos.com>
Link: https://lore.kernel.org/r/20220902100055.25724-3-guoqing.jiang@linux.dev
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Let's add some explanations here given the err handling is not obvious.

Signed-off-by: Guoqing Jiang <guoqing.jiang@linux.dev>
Acked-by: Md Haris Iqbal <haris.iqbal@ionos.com>
Link: https://lore.kernel.org/r/20220902100055.25724-2-guoqing.jiang@linux.dev
Signed-off-by: Jens Axboe <axboe@kernel.dk>

bio_check_ro() always return false now. Remove this unneeded return value
and cleanup the sole caller. No functional change intended.

Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Link: https://lore.kernel.org/r/20220905102754.1942-1-linmiaohe@huawei.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

If code reaches here, needs_restart must be true. Remove this unneeded
needs_restart check. No functional change intended.

Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Link: https://lore.kernel.org/r/20220905101950.4606-1-linmiaohe@huawei.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

The variable added is not effectively used in the function, so delete
it.

block/blk-map.c:273:16: warning: variable 'added' set but not used.

Link: https://bugzilla.openanolis.cn/show_bug.cgi?id=2049
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Link: https://lore.kernel.org/r/20220905063253.120082-1-jiapeng.chong@linux.alibaba.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

While doing code coverage testing while CONFIG_BLK_DEV_THROTTLING_LOW is
disabled, we found that there are many codes can never be reached.

This patch move such codes inside "#ifdef CONFIG_BLK_DEV_THROTTLING_LOW".

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220903062826.1099085-1-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

This reverts commit 16ede669

.

This is causing issues with CPU stalls on my test box, revert it for
now until we understand what is going on. It looks like infinite
looping off sbitmap_queue_wake_up(), but hard to tell with a lot of
CPUs hitting this issue and the console scrolling infinitely.

Link: https://lore.kernel.org/linux-block/e742813b-ce5c-0d58-205b-1626f639b1bd@kernel.dk/
Signed-off-by: Jens Axboe <axboe@kernel.dk>

This is useful for polled IO on a file, or for polled IO with the
io_uring passthrough mechanism. If bio allocations are done with
REQ_POLLED for those cases, then initializing the bio set with
BIOSET_PERCPU_CACHE enables the local per-cpu cache which eliminates
allocations (and frees) of bio structs when possible.

Reviewed-by: Kanchan Joshi <joshi.k@samsung.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Batched completions can clear multiple bits, but we're only decrementing
the wait_cnt by one each time. This can cause waiters to never be woken,
stalling IO. Use the batched count instead.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=215679
Signed-off-by: Keith Busch <kbusch@kernel.org>
Link: https://lore.kernel.org/r/20220825145312.1217900-1-kbusch@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

If "nr + nr_tags <= map_depth", then the value of nr_tags will not be
greater than map_depth, so no additional comparison is required.

Signed-off-by: Liu Song <liusong@linux.alibaba.com>
Link: https://lore.kernel.org/r/1661483653-27326-1-git-send-email-liusong@linux.alibaba.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Return the value from rtrs_clt_rdma_cq_direct() directly instead of
storing it in another redundant variable.

Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: ye xingchen <ye.xingchen@zte.com.cn>
Acked-by: Jack Wang <jinpu.wang@ionos.com>
Link: https://lore.kernel.org/r/20220824075213.221397-1-ye.xingchen@zte.com.cn
Signed-off-by: Jens Axboe <axboe@kernel.dk>

There are two problems can lead to lost wakeup:

1) invalid wakeup on the wrong waitqueue:

For example, 2 * wake_batch tags are put, while only wake_batch threads
are woken:

__sbq_wake_up
 atomic_cmpxchg -> reset wait_cnt
			__sbq_wake_up -> decrease wait_cnt
			...
			__sbq_wake_up -> wait_cnt is decreased to 0 again
			 atomic_cmpxchg
			 sbq_index_atomic_inc -> increase wake_index
			 wake_up_nr -> wake up and waitqueue might be empty
 sbq_index_atomic_inc -> increase again, one waitqueue is skipped
 wake_up_nr -> invalid wake up because old wakequeue might be empty

To fix the problem, increasing 'wake_index' before resetting 'wait_cnt'.

2) 'wait_cnt' can be decreased while waitqueue is empty

As pointed out by Jan Kara, following race is possible:

CPU1				CPU2
__sbq_wake_up			 __sbq_wake_up
 sbq_wake_ptr()			 sbq_wake_ptr() -> the same
 wait_cnt = atomic_dec_return()
 /* decreased to 0 */
 sbq_index_atomic_inc()
 /* move to next waitqueue */
 atomic_set()
 /* reset wait_cnt */
 wake_up_nr()
 /* wake up on the old waitqueue */
				 wait_cnt = atomic_dec_return()
				 /*
				  * decrease wait_cnt in the old
				  * waitqueue, while it can be
				  * empty.
				  */

Fix the problem by waking up before updating 'wake_index' and
'wait_cnt'.

With this patch, noted that 'wait_cnt' is still decreased in the old
empty waitqueue, however, the wakeup is redirected to a active waitqueue,
and the extra decrement on the old empty waitqueue is not handled.

Fixes: 88459642

 ("blk-mq: abstract tag allocation out into sbitmap library")
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20220803121504.212071-1-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Avoid a kmalloc+kfree for each page array, if we only have a few pages
that are mapped. An alloc+free for each IO is quite expensive, and
it's pretty pointless if we're only dealing with 1 or a few vecs.

Use UIO_FASTIOV like we do in other spots to set a sane limit for how
big of an IO we want to avoid allocations for.

Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

bdev based polled O_DIRECT is currently quite a bit faster than
passthru on the same device, and one of the reaons is that we're not
able to use the bio caching for passthru IO.

If REQ_POLLED is set on the request, use the fs bio set for grabbing a
bio from the caches, if available. This saves 5-6% of CPU over head
for polled passthru IO.

Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

We don't need full ints for several of these members. Change the
page_order and nr_entries to unsigned shorts, and the true/false from_user
and null_mapped to booleans.

This shrinks the struct from 32 to 24 bytes on 64-bit archs.

Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

'bfqd' can be accessed through 'bfqq->bfqd', there is no need to pass
it as a parameter separately.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20220816015631.1323948-4-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

'bfqq->bfqd' is ensured to set in bfq_init_queue(), and it will never
change afterwards.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20220816015631.1323948-3-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

While doing code coverage testing(CONFIG_BFQ_CGROUP_DEBUG is disabled), we
found that some functions doesn't have caller, thus remove them.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20220816015631.1323948-2-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Since blk_mq_map_queues() and the .map_queues() callbacks always return 0,
change their return type into void. Most callers ignore the returned value
anyway.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Keith Busch <kbusch@kernel.org>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: Doug Gilbert <dgilbert@interlog.com>
Cc: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: John Garry <john.garry@huawei.com>
Acked-by: Md Haris Iqbal <haris.iqbal@ionos.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Link: https://lore.kernel.org/r/20220815170043.19489-3-bvanassche@acm.org
[axboe: fold in fix from Bart]
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Instead of returning -EINVAL if an internal inconsistency is detected,
fall back to a single submission queue. This patch prepares for changing
the return value of the .map_queues() callbacks into void.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Keith Busch <kbusch@kernel.org>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20220815170043.19489-2-bvanassche@acm.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Add event tracing mechanism for following routines:
 - create_sess()
 - destroy_sess()
 - process_rdma()
 - process_msg_sess_info()
 - process_msg_open()
 - process_msg_close()

How to use:
1. Load the rnbd_server module
2. cd /sys/kernel/debug/tracing
3. If all the events need to be enabled:
        echo 1 > events/rnbd_srv/enable
4. OR only speific routine/event needs to be enabled e.g.
        echo 1 > events/rnbd_srv/create_sess/enable
5. cat trace
5. Run some workload which can trigger create_sess() routine/event

Signed-off-by: Santosh Pradhan <santosh.pradhan@ionos.com>
Signed-off-by: Jack Wang <jinpu.wang@ionos.com>
Signed-off-by: Md Haris Iqbal <haris.iqbal@ionos.com>
Link: https://lore.kernel.org/r/20220818105551.110490-2-haris.iqbal@ionos.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Provide a mechanism to retrieve basic status information about
the device, including the "supported" flag indicating whether
SED-OPAL is supported. The information returned is from the various
feature descriptors received during the discovery0 step, and so
this ioctl does nothing more than perform the discovery0 step
and then save the information received. See "struct opal_status"
and OPAL_FL_* bits for the status information currently returned.

This is necessary to be able to check whether a device is OPAL
enabled, set up, locked or unlocked from userspace programs
like systemd-cryptsetup and libcryptsetup. Right now we just
have to assume the user 'knows' or blindly attempt setup/lock/unlock
operations.

Signed-off-by: Douglas Miller <dougmill@linux.vnet.ibm.com>
Tested-by: Luca Boccassi <bluca@debian.org>
Reviewed-by: Scott Bauer <sbauer@plzdonthack.me>
Acked-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Link: https://lore.kernel.org/r/20220816140713.84893-1-luca.boccassi@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Pull irq fixes from Ingo Molnar:
 "Misc irqchip fixes: LoongArch driver fixes and a Hyper-V IOMMU fix"

* tag 'irq-urgent-2022-08-21' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  irqchip/loongson-liointc: Fix an error handling path in liointc_init()
  irqchip/loongarch: Fix irq_domain_alloc_fwnode() abuse
  irqchip/loongson-pch-pic: Move find_pch_pic() into CONFIG_ACPI
  irqchip/loongson-eiointc: Fix a build warning
  irqchip/loongson-eiointc: Fix irq affinity setting
  iommu/hyper-v: Use helper instead of directly accessing affinity

Pull x86 kprobes fix from Ingo Molnar:
 "Fix a kprobes bug in JNG/JNLE emulation when a kprobe is installed at
  such instructions, possibly resulting in incorrect execution (the
  wrong branch taken)"

* tag 'perf-urgent-2022-08-21' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/kprobes: Fix JNG/JNLE emulation

Pull tracing fixes from Steven Rostedt:
 "Various fixes for tracing:

   - Fix a return value of traceprobe_parse_event_name()

   - Fix NULL pointer dereference from failed ftrace enabling

   - Fix NULL pointer dereference when asking for registers from eprobes

   - Make eprobes consistent with kprobes/uprobes, filters and
     histograms"

* tag 'trace-v6.0-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  tracing: Have filter accept "common_cpu" to be consistent
  tracing/probes: Have kprobes and uprobes use $COMM too
  tracing/eprobes: Have event probes be consistent with kprobes and uprobes
  tracing/eprobes: Fix reading of string fields
  tracing/eprobes: Do not hardcode $comm as a string
  tracing/eprobes: Do not allow eprobes to use $stack, or % for regs
  ftrace: Fix NULL pointer dereference in is_ftrace_trampoline when ftrace is dead
  tracing/perf: Fix double put of trace event when init fails
  tracing: React to error return from traceprobe_parse_event_name()

Make filtering consistent with histograms. As "cpu" can be a field of an
event, allow for "common_cpu" to keep it from being confused with the
"cpu" field of the event.

Link: https://lkml.kernel.org/r/20220820134401.513062765@goodmis.org
Link: https://lore.kernel.org/all/20220820220920.e42fa32b70505b1904f0a0ad@kernel.org/

Cc: stable@vger.kernel.org
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Tzvetomir Stoyanov <tz.stoyanov@gmail.com>
Cc: Tom Zanussi <zanussi@kernel.org>
Fixes: 1e3bac71

 ("tracing/histogram: Rename "cpu" to "common_cpu"")
Suggested-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Both $comm and $COMM can be used to get current->comm in eprobes and the
filtering and histogram logic. Make kprobes and uprobes consistent in this
regard and allow both $comm and $COMM as well. Currently kprobes and
uprobes only handle $comm, which is inconsistent with the other utilities,
and can be confusing to users.

Link: https://lkml.kernel.org/r/20220820134401.317014913@goodmis.org
Link: https://lore.kernel.org/all/20220820220442.776e1ddaf8836e82edb34d01@kernel.org/

Cc: stable@vger.kernel.org
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Tzvetomir Stoyanov <tz.stoyanov@gmail.com>
Cc: Tom Zanussi <zanussi@kernel.org>
Fixes: 53305928

 ("tracing: probeevent: Introduce new argument fetching code")
Suggested-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Currently, if a symbol "@" is attempted to be used with an event probe
(eprobes), it will cause a NULL pointer dereference crash.

Both kprobes and uprobes can reference data other than the main registers.
Such as immediate address, symbols and the current task name. Have eprobes
do the same thing.

For "comm", if "comm" is used and the event being attached to does not
have the "comm" field, then make it the "$comm" that kprobes has. This is
consistent to the way histograms and filters work.

Link: https://lkml.kernel.org/r/20220820134401.136924220@goodmis.org

Cc: stable@vger.kernel.org
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Tzvetomir Stoyanov <tz.stoyanov@gmail.com>
Cc: Tom Zanussi <zanussi@kernel.org>
Fixes: 7491e2c4

 ("tracing: Add a probe that attaches to trace events")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Currently when an event probe (eprobe) hooks to a string field, it does
not display it as a string, but instead as a number. This makes the field
rather useless. Handle the different kinds of strings, dynamic, static,
relational/dynamic etc.

Now when a string field is used, the ":string" type can be used to display
it:

  echo "e:sw sched/sched_switch comm=$next_comm:string" > dynamic_events

Link: https://lkml.kernel.org/r/20220820134400.959640191@goodmis.org

Cc: stable@vger.kernel.org
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Tzvetomir Stoyanov <tz.stoyanov@gmail.com>
Cc: Tom Zanussi <zanussi@kernel.org>
Fixes: 7491e2c4

 ("tracing: Add a probe that attaches to trace events")
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

The variable $comm is hard coded as a string, which is true for both
kprobes and uprobes, but for event probes (eprobes) it is a field name. In
most cases the "comm" field would be a string, but there's no guarantee of
that fact.

Do not assume that comm is a string. Not to mention, it currently forces
comm fields to fault, as string processing for event probes is currently
broken.

Link: https://lkml.kernel.org/r/20220820134400.756152112@goodmis.org

Cc: stable@vger.kernel.org
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Tzvetomir Stoyanov <tz.stoyanov@gmail.com>
Cc: Tom Zanussi <zanussi@kernel.org>
Fixes: 7491e2c4

 ("tracing: Add a probe that attaches to trace events")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

While playing with event probes (eprobes), I tried to see what would
happen if I attempted to retrieve the instruction pointer (%rip) knowing
that event probes do not use pt_regs. The result was:

 BUG: kernel NULL pointer dereference, address: 0000000000000024
 #PF: supervisor read access in kernel mode
 #PF: error_code(0x0000) - not-present page
 PGD 0 P4D 0
 Oops: 0000 [#1] PREEMPT SMP PTI
 CPU: 1 PID: 1847 Comm: trace-cmd Not tainted 5.19.0-rc5-test+ #309
 Hardware name: Hewlett-Packard HP Compaq Pro 6300 SFF/339A, BIOS K01
v03.03 07/14/2016
 RIP: 0010:get_event_field.isra.0+0x0/0x50
 Code: ff 48 c7 c7 c0 8f 74 a1 e8 3d 8b f5 ff e8 88 09 f6 ff 4c 89 e7 e8
50 6a 13 00 48 89 ef 5b 5d 41 5c 41 5d e9 42 6a 13 00 66 90 <48> 63 47 24
8b 57 2c 48 01 c6 8b 47 28 83 f8 02 74 0e 83 f8 04 74
 RSP: 0018:ffff916c394bbaf0 EFLAGS: 00010086
 RAX: ffff916c854041d8 RBX: ffff916c8d9fbf50 RCX: ffff916c255d2000
 RDX: 0000000000000000 RSI: ffff916c255d2008 RDI: 0000000000000000
 RBP: 0000000000000000 R08: ffff916c3a2a0c08 R09: ffff916c394bbda8
 R10: 0000000000000000 R11: 0000000000000000 R12: ffff916c854041d8
 R13: ffff916c854041b0 R14: 0000000000000000 R15: 0000000000000000
 FS:  0000000000000000(0000) GS:ffff916c9ea40000(0000)
knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 0000000000000024 CR3: 000000011b60a002 CR4: 00000000001706e0
 Call Trace:
  <TASK>
  get_eprobe_size+0xb4/0x640
  ? __mod_node_page_state+0x72/0xc0
  __eprobe_trace_func+0x59/0x1a0
  ? __mod_lruvec_page_state+0xaa/0x1b0
  ? page_remove_file_rmap+0x14/0x230
  ? page_remove_rmap+0xda/0x170
  event_triggers_call+0x52/0xe0
  trace_event_buffer_commit+0x18f/0x240
  trace_event_raw_event_sched_wakeup_template+0x7a/0xb0
  try_to_wake_up+0x260/0x4c0
  __wake_up_common+0x80/0x180
  __wake_up_common_lock+0x7c/0xc0
  do_notify_parent+0x1c9/0x2a0
  exit_notify+0x1a9/0x220
  do_exit+0x2ba/0x450
  do_group_exit+0x2d/0x90
  __x64_sys_exit_group+0x14/0x20
  do_syscall_64+0x3b/0x90
  entry_SYSCALL_64_after_hwframe+0x46/0xb0

Obviously this is not the desired result.

Move the testing for TPARG_FL_TPOINT which is only used for event probes
to the top of the "$" variable check, as all the other variables are not
used for event probes. Also add a check in the register parsing "%" to
fail if an event probe is used.

Link: https://lkml.kernel.org/r/20220820134400.564426983@goodmis.org

Cc: stable@vger.kernel.org
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Tzvetomir Stoyanov <tz.stoyanov@gmail.com>
Cc: Tom Zanussi <zanussi@kernel.org>
Fixes: 7491e2c4

 ("tracing: Add a probe that attaches to trace events")
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>