Re: [FYI][PATCH] tracing/treewide: Remove second parameter of __assign_str()

On Thu, 14 Mar 2024 09:57:57 -0700 Alison Schofield wrote: > On Fri, Feb 23, 2024 at 12:56:34PM -0500, Steven Rostedt wrote: > > From: "Steven Rostedt (Google)" > > > > [ > >This is a treewide change. I will likely re-create this patch again in >

Re: [PATCH] net: hns3: tracing: fix hclgevf trace event strings

On Thu, 14 Mar 2024 15:39:28 +0100 Paolo Abeni wrote: > On Wed, 2024-03-13 at 09:34 -0400, Steven Rostedt wrote: > > From: "Steven Rostedt (Google)" > > > > [ > >Note, I need to take this patch through my tree, so I'm looking for > > acks. &g

Re: [PATCH] tracing: Use strcmp() in __assign_str() WARN_ON() check

On Wed, 13 Mar 2024 13:45:50 -0400 Steven Rostedt wrote: > Let me test to make sure that when src is a string "like this" that it does > the strcmp(). Otherwise, we may have to always do the strcmp(), which I > really would like to avoid. I added the below patch and e

Re: [PATCH] tracing: Use strcmp() in __assign_str() WARN_ON() check

On Wed, 13 Mar 2024 09:59:03 -0700 Nathan Chancellor wrote: > > Reported-by: kernel test robot > > Closes: > > https://lore.kernel.org/oe-kbuild-all/202402292111.kidexylu-...@intel.com/ > > Fixes: 433e1d88a3be ("tracing: Add warning if string in __assign_str() does > > not match __string()")

[PATCH] net: hns3: tracing: fix hclgevf trace event strings

From: "Steven Rostedt (Google)" [ Note, I need to take this patch through my tree, so I'm looking for acks. This causes the build to fail when I add the __assign_str() check, which I was about to push to Linus, but it breaks allmodconfig due to this error. ] Th

[PATCH v4] ring-buffer: Have mmapped ring buffer keep track of missed events

From: "Steven Rostedt (Google)" While testing libtracefs on the mmapped ring buffer, the test that checks if missed events are accounted for failed when using the mapped buffer. This is because the mapped page does not update the missed events that were dropped because the writer

[PATCH] ring-buffer: Do not set shortest_full when full target is hit

From: "Steven Rostedt (Google)" The rb_watermark_hit() checks if the amount of data in the ring buffer is above the percentage level passed in by the "full" variable. If it is, it returns true. But it also sets the "shortest_full" field of the cpu_buffer that

Re: [PATCH v2 2/2] ring-buffer: Reuse rb_watermark_hit() for the poll logic

On Wed, 13 Mar 2024 00:38:42 +0900 Masami Hiramatsu (Google) wrote: > On Tue, 12 Mar 2024 09:19:21 -0400 > Steven Rostedt wrote: > > > From: "Steven Rostedt (Google)" > > > > The check for knowing if the poll should wait or not is basically the >

Re: [PATCH v2 1/2] ring-buffer: Fix full_waiters_pending in poll

On Wed, 13 Mar 2024 00:22:10 +0900 Masami Hiramatsu (Google) wrote: > On Tue, 12 Mar 2024 09:19:20 -0400 > Steven Rostedt wrote: > > > From: "Steven Rostedt (Google)" > > > > If a reader of the ring buffer is doing a poll, and waiting for the ring &

[PATCH] tracing: Use strcmp() in __assign_str() WARN_ON() check

From: "Steven Rostedt (Google)" The WARN_ON() check in __assign_str() to catch where the source variable to the macro doesn't match the source variable to __string() gives an error in clang: >> include/trace/events/sunrpc.h:703:4: warning: result of comparison against a &

[PATCH v2 1/2] ring-buffer: Fix full_waiters_pending in poll

From: "Steven Rostedt (Google)" If a reader of the ring buffer is doing a poll, and waiting for the ring buffer to hit a specific watermark, there could be a case where it gets into an infinite ping-pong loop. The poll code has: rbwork->full_waiters_pending = true; if

[PATCH v2 0/2] ring-buffer: Fix poll wakeup logic

nd !full wakeups. But since poll uses the same logic for full wakeups it can just call that function with full set. Changes since v1: https://lore.kernel.org/all/20240312115455.666920...@goodmis.org/ - Removed unused 'flags' in ring_buffer_poll_wait() as the spin_lock is now in rb_watermark_hit(). Steve

[PATCH v2 2/2] ring-buffer: Reuse rb_watermark_hit() for the poll logic

From: "Steven Rostedt (Google)" The check for knowing if the poll should wait or not is basically the exact same logic as rb_watermark_hit(). The only difference is that rb_watermark_hit() also handles the !full case. But for the full case, the logic is the same. Just call th

[PATCH v4 2/2] tracing/ring-buffer: Fix wait_on_pipe() race

From: "Steven Rostedt (Google)" When the trace_pipe_raw file is closed, there should be no new readers on the file descriptor. This is mostly handled with the waking and wait_index fields of the iterator. But there's still a slight race. CPU 0

[PATCH v4 0/2] tracing/ring-buffer: Fix wakeup of ring buffer waiters

tps://lore.kernel.org/lkml/20240308183816.676883...@goodmis.org/ - My tests triggered a warning about calling a mutex_lock() after a prepare_to_wait() that changed the task's state. Convert the affected mutex over to a spinlock. Steven Rostedt (Google) (2): ring-buffer: Use wait_even

[PATCH v4 1/2] ring-buffer: Use wait_event_interruptible() in ring_buffer_wait()

From: "Steven Rostedt (Google)" Convert ring_buffer_wait() over to wait_event_interruptible(). The default condition is to execute the wait loop inside __wait_event() just once. This does not change the ring_buffer_wait() prototype yet, but restructures the code so that it can ta

[PATCH v3 2/2] tracing/ring-buffer: Fix wait_on_pipe() race

From: "Steven Rostedt (Google)" When the trace_pipe_raw file is closed, there should be no new readers on the file descriptor. This is mostly handled with the waking and wait_index fields of the iterator. But there's still a slight race. CPU 0

[PATCH v3 0/2] tracing/ring-buffer: Fix wakeup of ring buffer waiters

mutex_lock() after a prepare_to_wait() that changed the task's state. Convert the affected mutex over to a spinlock. Steven Rostedt (Google) (2): ring-buffer: Use wait_event_interruptible() in ring_buffer_wait() tracing/ring-buffer: Fix wait_on_pipe() race include/linux/

[PATCH v3 1/2] ring-buffer: Use wait_event_interruptible() in ring_buffer_wait()

From: "Steven Rostedt (Google)" Convert ring_buffer_wait() over to wait_event_interruptible(). The default condition is to execute the wait loop inside __wait_event() just once. This does not change the ring_buffer_wait() prototype yet, but restructures the code so that it can ta

[PATCH 2/2] ring-buffer: Reuse rb_watermark_hit() for the poll logic

From: "Steven Rostedt (Google)" The check for knowing if the poll should wait or not is basically the exact same logic as rb_watermark_hit(). The only difference is that rb_watermark_hit() also handles the !full case. But for the full case, the logic is the same. Just call th

[PATCH 1/2] ring-buffer: Fix full_waiters_pending in poll

From: "Steven Rostedt (Google)" If a reader of the ring buffer is doing a poll, and waiting for the ring buffer to hit a specific watermark, there could be a case where it gets into an infinite ping-pong loop. The poll code has: rbwork->full_waiters_pending = true; if

[PATCH 0/2] ring-buffer: Fix poll wakeup logic

nd !full wakeups. But since poll uses the same logic for full wakeups it can just call that function with full set. Steven Rostedt (Google) (2): ring-buffer: Fix full_waiters_pending in poll ring-buffer: Reuse rb_watermark_hit() for the poll logic kernel/trace/ring_buffer.c | 30 +++--- 1 file changed, 19 insertions(+), 11 deletions(-)

Re: [PATCH 0/6] tracing/ring-buffer: Fix wakeup of ring buffer waiters

On Fri, 8 Mar 2024 13:41:59 -0800 Linus Torvalds wrote: > On Fri, 8 Mar 2024 at 13:39, Linus Torvalds > wrote: > > > > So the above "complexity" is *literally* just changing the > > > > (new = atomic_read_acquire(>seq)) != old > > > > condition to > > > >

Re: [PATCH 0/8] tracing: Persistent traces across a reboot or crash

On Sat, 9 Mar 2024 10:27:47 -0800 Kees Cook wrote: > On Tue, Mar 05, 2024 at 08:59:10PM -0500, Steven Rostedt wrote: > > This is a way to map a ring buffer instance across reboots. > > As mentioned on Fedi, check out the persistent storage subsystem > (pstore)[1]. It alread

Re: [PATCH 0/6] tracing/ring-buffer: Fix wakeup of ring buffer waiters

On Fri, 8 Mar 2024 12:39:10 -0800 Linus Torvalds wrote: > On Fri, 8 Mar 2024 at 10:38, Steven Rostedt wrote: > > > > A patch was sent to "fix" the wait_index variable that is used to help with > > waking of waiters on the ring buffer. The patch was reje

[PATCH v2 6/6] tracing/ring-buffer: Fix wait_on_pipe() race

From: "Steven Rostedt (Google)" When the trace_pipe_raw file is closed, there should be no new readers on the file descriptor. This is mostly handled with the waking and wait_index fields of the iterator. But there's still a slight race. CPU 0

[PATCH v2 5/6] ring-buffer: Restructure ring_buffer_wait() to prepare for updates

From: "Steven Rostedt (Google)" The ring_buffer_wait() needs to be broken into three functions for proper synchronization from the context of the callers: ring_buffer_prepare_to_wait() ring_buffer_wait() ring_buffer_finish_wait() To simplify the process, pull out the logic f

[PATCH v2 4/6] tracing: Fix waking up tracing readers

From: "Steven Rostedt (Google)" When the tracing_pipe_raw file is closed, if there are readers still blocked on it, they need to be woken up. Currently a wait_index is used. When the readers need to be woken, the index is updated and they are all woken up. But there is a race where a

[PATCH v2 3/6] tracing: Use .flush() call to wake up readers

From: "Steven Rostedt (Google)" The .release() function does not get called until all readers of a file descriptor are finished. If a thread is blocked on reading a file descriptor in ring_buffer_wait(), and another thread closes the file descriptor, it will not wake up the ot

[PATCH v2 2/6] ring-buffer: Fix resetting of shortest_full

From: "Steven Rostedt (Google)" The "shortest_full" variable is used to keep track of the waiter that is waiting for the smallest amount on the ring buffer before being woken up. When a tasks waits on the ring buffer, it passes in a "full" value that is a percentag

[PATCH v2 1/6] ring-buffer: Fix waking up ring buffer readers

From: "Steven Rostedt (Google)" A task can wait on a ring buffer for when it fills up to a specific watermark. The writer will check the minimum watermark that waiters are waiting for and if the ring buffer is past that, it will wake up all the waiters. The waiters are in a

[PATCH v2 0/6] tracing/ring-buffer: Fix wakeup of ring buffer waiters

r a prepare_to_wait() that changed the task's state. Convert the affected mutex over to a spinlock. Steven Rostedt (Google) (6): ring-buffer: Fix waking up ring buffer readers ring-buffer: Fix resetting of shortest_full tracing: Use .flush() call to wake up readers tra

Re: [PATCH 4/6] tracing: Fix waking up tracing readers

On Fri, 08 Mar 2024 13:38:20 -0500 Steven Rostedt wrote: > +static DEFINE_MUTEX(wait_mutex); > + > +static bool wait_woken_prepare(struct trace_iterator *iter, int *wait_index) > +{ > + bool woken = false; > + > + mutex_lock(_mutex); > + if (iter->waking) &

[PATCH 5/6] ring-buffer: Restructure ring_buffer_wait() to prepare for updates

From: "Steven Rostedt (Google)" The ring_buffer_wait() needs to be broken into three functions for proper synchronization from the context of the callers: ring_buffer_prepare_to_wait() ring_buffer_wait() ring_buffer_finish_wait() To simplify the process, pull out the logic f

[PATCH 6/6] tracing/ring-buffer: Fix wait_on_pipe() race

From: "Steven Rostedt (Google)" When the trace_pipe_raw file is closed, there should be no new readers on the file descriptor. This is mostly handled with the waking and wait_index fields of the iterator. But there's still a slight race. CPU 0

[PATCH 3/6] tracing: Use .flush() call to wake up readers

From: "Steven Rostedt (Google)" The .release() function does not get called until all readers of a file descriptor are finished. If a thread is blocked on reading a file descriptor in ring_buffer_wait(), and another thread closes the file descriptor, it will not wake up the ot

[PATCH 2/6] ring-buffer: Fix resetting of shortest_full

From: "Steven Rostedt (Google)" The "shortest_full" variable is used to keep track of the waiter that is waiting for the smallest amount on the ring buffer before being woken up. When a tasks waits on the ring buffer, it passes in a "full" value that is a percentag

[PATCH 4/6] tracing: Fix waking up tracing readers

From: "Steven Rostedt (Google)" When the tracing_pipe_raw file is closed, if there are readers still blocked on it, they need to be woken up. Currently a wait_index is used. When the readers need to be woken, the index is updated and they are all woken up. But there is a race where a

[PATCH 1/6] ring-buffer: Fix waking up ring buffer readers

From: "Steven Rostedt (Google)" A task can wait on a ring buffer for when it fills up to a specific watermark. The writer will check the minimum watermark that waiters are waiting for and if the ring buffer is past that, it will wake up all the waiters. The waiters are in a

[PATCH 0/6] tracing/ring-buffer: Fix wakeup of ring buffer waiters

if its own condition has been set (in this case: iter->waking) and then sleep. Follows the same semantics as any other wait logic. Steven Rostedt (Google) (6): ring-buffer: Fix waking up ring buffer readers ring-buffer: Fix resetting of shortest_full tracing: Use .flush()

Re: [PATCH v2] workqueue: add function in event of workqueue_activate_work

> Signed-off-by: Kassey Li > --- > Changelog: > v1: > https://lore.kernel.org/all/20240308010929.1955339-1-quic_yinga...@quicinc.com/ > v1->v2: > - do not follow checkpatch in TRACE_EVENT() macros > - add sample "workqueue_activate_work: work struct ff80413a78b

Re: [PATCH] workqueue: add function in event of workqueue_activate_work

On Fri, 8 Mar 2024 09:09:29 +0800 Kassey Li wrote: > The trace event "workqueue_activate_work" only print work struct. > However, function is the region of interest in a full sequence of work. > Current workqueue_activate_work trace event output: > > workqueue_activate_work: work struct

Re: [PATCH] ring-buffer: mark racy accesses on work->wait_index

On Wed, 6 Mar 2024 10:55:34 +0800 linke li wrote: > Mark data races to work->wait_index as benign using READ_ONCE and WRITE_ONCE. > These accesses are expected to be racy. Are we now to the point that every single access of a variable (long size or less) needs a READ_ONCE/WRITE_ONCE even with

[POC] !!! Re: [PATCH 0/8] tracing: Persistent traces across a reboot or crash

I forgot to add [POC] to the topic. All these patches are a proof of concept. -- Steve

[PATCH 8/8] ring-buffer: Validate boot range memory events

From: "Steven Rostedt (Google)" Make sure all the events in each of the sub-buffers that were mapped in a memory region are valid. This moves the code that walks the buffers for time-stamp validation out of the CONFIG_RING_BUFFER_VALIDATE_TIME_DELTAS ifdef block and is used t

[PATCH 7/8] ring-buffer: Add test if range of boot buffer is valid

From: "Steven Rostedt (Google)" Add a test against the ring buffer memory range to see if it has valid data. The ring_buffer_meta structure is given a new field called "first_buffer" which holds the address of the first sub-buffer. This is used to both determine if the ot

[PATCH 5/8] ring-buffer: Add ring_buffer_meta data

From: "Steven Rostedt (Google)" Populate the ring_buffer_meta array. It holds the pointer to the head_buffer (next to read), the commit_buffer (next to write) the size of the sub-buffers, number of sub-buffers and an array that keeps track of the order of the sub-buffers. This i

[PATCH 6/8] ring-buffer: Add output of ring buffer meta page

From: "Steven Rostedt (Google)" Add a buffer_meta per-cpu file for the trace instance that is mapped to boot memory. This shows the current meta-data and can be used by user space tools to record off the current mappings to help reconstruct the ring buffer after a reboot. It does not

[PATCH 3/8] tracing: Create "boot_mapped" instance for memory mapped buffer

From: "Steven Rostedt (Google)" Add two global variables trace_buffer_start and trace_buffer_size. If they are both set, then a "boot_mapped" instance will be created using the memory specified by these variables as its ring buffer. The instance will exist in: /sys/kern

[PATCH 4/8] HACK: Hard code in mapped tracing buffer address

From: "Steven Rostedt (Google)" Do not submit! This is for testing purposes only. It hard codes an address that I was using to store the ring buffer range. How the memory actually gets mapped will be another project. Signed-off-by: Steven Rostedt (Google) --- arch/x86/kernel/se

[PATCH 2/8] ring-buffer: Add ring_buffer_alloc_range()

From: "Steven Rostedt (Google)" In preparation to allowing the trace ring buffer to be allocated in a range of memory that is persistent across reboots, add ring_buffer_alloc_range(). It takes a contiguous range of memory and will split it up evening for the per CPU ring buffers.

[PATCH 0/8] tracing: Persistent traces across a reboot or crash

trace and it will have the trace. I'm sure there's still some gotchas here, which is why this is currently still just a POC. Enjoy... Steven Rostedt (Google) (8): ring-buffer: Allow mapped field to be set without mapping ring-buffer: Add ring_buffer_alloc_range() traci

[PATCH 1/8] ring-buffer: Allow mapped field to be set without mapping

From: "Steven Rostedt (Google)" In preparation for having the ring buffer mapped to a dedicated location, which will have the same restrictions as user space memory mapped buffers, allow it to use the "mapped" field of the ring_buffer_per_cpu structure without having the

[PATCH v2] tracing: Limit trace_marker writes to just 4K

From: "Steven Rostedt (Google)" Limit the max print event of trace_marker to just 4K string size. This must also be less than the amount that can be held by a trace_seq along with the text that is before the output (like the task name, PID, CPU, state, etc). As trace_seq is made to ha

Re: [PATCH] tracing: Have trace_marker writes be just half of TRACE_SEQ_SIZE

On Mon, 4 Mar 2024 21:48:44 -0500 Mathieu Desnoyers wrote: > On 2024-03-04 21:37, Steven Rostedt wrote: > > On Mon, 4 Mar 2024 21:35:38 -0500 > > Steven Rostedt wrote: > > > >>> And it's not for debugging, it's for validation of assumptions > >>

Re: [PATCH] tracing: Have trace_marker writes be just half of TRACE_SEQ_SIZE

On Mon, 4 Mar 2024 21:35:38 -0500 Steven Rostedt wrote: > > And it's not for debugging, it's for validation of assumptions > > made about an upper bound limit defined for a compile-time > > check, so as the code evolves issues are caught early. > > validating is debug

Re: [PATCH] tracing: Have trace_marker writes be just half of TRACE_SEQ_SIZE

On Mon, 4 Mar 2024 21:18:13 -0500 Mathieu Desnoyers wrote: > On 2024-03-04 20:59, Steven Rostedt wrote: > > On Mon, 4 Mar 2024 20:42:39 -0500 > > Mathieu Desnoyers wrote: > > > >> #define TRACE_OUTPUT_META_DATA_MAX_LEN 80 > >> > >

Re: [PATCH] tracing: Have trace_marker writes be just half of TRACE_SEQ_SIZE

On Mon, 4 Mar 2024 20:42:39 -0500 Mathieu Desnoyers wrote: > #define TRACE_OUTPUT_META_DATA_MAX_LEN80 > > and a runtime check in the code generating this header. > > This would avoid adding an unchecked upper limit. That would be a lot of complex code that is for debugging

Re: [PATCH] tracing: Have trace_marker writes be just half of TRACE_SEQ_SIZE

On Mon, 4 Mar 2024 20:36:28 -0500 Mathieu Desnoyers wrote: > > <...>-999 [001] . 2296.140373: tracing_mark_write: > > hello > > ^^^ > > This is the meta data that is added to trace_seq > > If this

Re: [PATCH] tracing: Have trace_marker writes be just half of TRACE_SEQ_SIZE

On Mon, 4 Mar 2024 20:35:16 -0500 Steven Rostedt wrote: > > BUILD_BUG_ON(TRACING_MARK_MAX_SIZE + sizeof(meta data stuff...) > > > TRACE_SEQ_SIZE); > > That's not the meta size I'm worried about. The sizeof(meta data) is the > raw event binary data, which is

Re: [PATCH] tracing: Have trace_marker writes be just half of TRACE_SEQ_SIZE

On Mon, 4 Mar 2024 20:15:57 -0500 Mathieu Desnoyers wrote: > On 2024-03-04 19:27, Steven Rostedt wrote: > > From: "Steven Rostedt (Google)" > > > > Since the size of trace_seq's buffer is the max an event can output, have > > the trace_marker be half of t

Re: [PATCH] tracing: Have trace_marker writes be just half of TRACE_SEQ_SIZE

On Mon, 4 Mar 2024 16:43:46 -0800 Randy Dunlap wrote: > > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c > > index 8198bfc54b58..d68544aef65f 100644 > > --- a/kernel/trace/trace.c > > +++ b/kernel/trace/trace.c > > @@ -7320,6 +7320,17 @@ tracing_mark_write(struct file *filp, const char

[PATCH] tracing: Have trace_marker writes be just half of TRACE_SEQ_SIZE

From: "Steven Rostedt (Google)" Since the size of trace_seq's buffer is the max an event can output, have the trace_marker be half of the entire TRACE_SEQ_SIZE, which is 4K. That will keep writes that has meta data written from being dropped (but reported), because the total output of

Re: [PATCH] tracing: Remove precision vsnprintf() check from print event

On Mon, 4 Mar 2024 18:55:00 -0500 Steven Rostedt wrote: > On Mon, 4 Mar 2024 18:23:41 -0500 > Mathieu Desnoyers wrote: > > > It appears to currently be limited by > > > > #define TRACE_SEQ_BUFFER_SIZE (PAGE_SIZE * 2 - \ > > (sizeof(struct seq_b

[PATCH] tracing: Limit trace_seq size to just 8K and not depend on architecture PAGE_SIZE

From: "Steven Rostedt (Google)" The trace_seq buffer is used to print out entire events. It's typically set to PAGE_SIZE * 2 as there's some events that can be quite large. As a side effect, writes to trace_marker is limited by both the size of the trace_seq buffer as well as the rin

Re: [PATCH] tracing: Remove precision vsnprintf() check from print event

On Mon, 4 Mar 2024 18:23:41 -0500 Mathieu Desnoyers wrote: > It appears to currently be limited by > > #define TRACE_SEQ_BUFFER_SIZE (PAGE_SIZE * 2 - \ > (sizeof(struct seq_buf) + sizeof(size_t) + sizeof(int))) > > checked within tracing_mark_write(). Yeah, I can hard code this to

[PATCH] tracing: Remove precision vsnprintf() check from print event

From: "Steven Rostedt (Google)" This reverts 60be76eeabb3d ("tracing: Add size check when printing trace_marker output"). The only reason the precision check was added was because of a bug that miscalculated the write size of the string into the ring buffer and it t

Re: [PATCH RFC ftrace] Chose RCU Tasks based on TASKS_RCU rather than PREEMPTION

On Fri, 1 Mar 2024 12:25:10 -0800 "Paul E. McKenney" wrote: > > That would work for me. If there are no objections, I will make this > > change. > > But I did check the latency of synchronize_rcu_tasks_rude() (about 100ms) > and synchronize_rcu() (about 20ms). This is on a

Re: [PATCH] ring-buffer: use READ_ONCE() to read cpu_buffer->commit_page in concurrent environment

On Fri, 1 Mar 2024 11:37:54 -0500 Mathieu Desnoyers wrote: > On 2024-03-01 10:49, Steven Rostedt wrote: > > On Fri, 1 Mar 2024 13:37:18 +0800 > > linke wrote: > > > >>> So basically you are worried about read-tearing? > >>> > >>>

Re: [PATCH] ring-buffer: use READ_ONCE() to read cpu_buffer->commit_page in concurrent environment

On Fri, 1 Mar 2024 13:37:18 +0800 linke wrote: > > So basically you are worried about read-tearing? > > > > That wasn't mentioned in the change log. > > Yes. Sorry for making this confused, I am not very familiar with this and > still learning. No problem. We all have to learn this anyway.

Re: How to display a ktime value as trace timestamp in trace output?

On Wed, 31 Jan 2024 14:47:31 + David Howells wrote: > Hi Steven, Hi David, Sorry, I just noticed this email as it was buried in other unread emails :-p > > I have a tracepoint in AF_RXRPC that displays information about a timeout I'm > going to set. I have the timeout in a ktime_t as an

Re: [PATCH] ring-buffer: use READ_ONCE() to read cpu_buffer->commit_page in concurrent environment

On Thu, 29 Feb 2024 20:32:26 +0800 linke wrote: > Hi Steven, sorry for the late reply. > > > > > Now the reason for the above READ_ONCE() is because the variables *are* > > going to be used again. We do *not* want the compiler to play any games > > with that. > > > > I don't think it is

Re: [PATCH RFC ftrace] Chose RCU Tasks based on TASKS_RCU rather than PREEMPTION

just might > happen within a trampoline. > > Therefore, update ftrace_shutdown() to invoke synchronize_rcu_tasks() > based on CONFIG_TASKS_RCU instead of CONFIG_PREEMPTION. > > Only build tested. > > Signed-off-by: Paul E. McKenney > Cc: Steven Rostedt > Cc: Ma

[PATCH] tracepoints: Use WARN() and not WARN_ON() for warnings

From: "Steven Rostedt (Google)" There are two WARN_ON*() warnings in tracepoint.h that deal with RCU usage. But when they trigger, especially from using a TRACE_EVENT() macro, the information is not very helpful and is confusing: [ cut here ] WARNING: CPU

Re: tprobe event tracing error

On Wed, 28 Feb 2024 10:52:52 -0500 Steven Rostedt wrote: > The prototype of fchownat() is: > > int fchmodat(int dirfd, const char *pathname, mode_t mode, int flags); > > Where pathname is the third parameter, not the first, and mode is the third. I meant pathname is the s

Re: tprobe event tracing error

On Wed, 28 Feb 2024 17:25:40 +0300 Максим Морсков wrote: > Dear colleagues, > One last question — is it bug or feature that trobe event tracing can not > correctly dereference string pointers from pt_regs? > For example: > echo 't:tmy_chmod sys_enter id=$arg2 filename=+8($arg1):string >

Re: [PATCH v2] mm: add alloc_contig_migrate_range allocation statistics

nsigned long end, > + unsigned long nr_migrated, > + unsigned long nr_reclaimed, > + unsigned long nr_mapped, > + int migratetype), Well, you didn't need to change the order of the parameters. Anyway, from a tracing point of view:

[PATCH] tracing: Prevent trace_marker being bigger than unsigned short

From: "Steven Rostedt (Google)" The trace_marker write goes into the ring buffer. A test was added to write a string as big as the sub-buffer of the ring buffer to see if it would work. A sub-buffer is typically PAGE_SIZE in length. On PowerPC architecture, the ftrace selftest for tr

Re: [PATCH] net/ipv4: add tracepoint for icmp_send

On Tue, 27 Feb 2024 10:50:36 +0800 (CST) wrote: > include/trace/events/icmp.h | 57 > + > net/ipv4/icmp.c | 4 > 2 files changed, 61 insertions(+) > create mode 100644 include/trace/events/icmp.h > > diff --git

Re: [PATCH] ring-buffer: use READ_ONCE() to read cpu_buffer->commit_page in concurrent environment

On Sun, 25 Feb 2024 15:03:02 -0500 Steven Rostedt wrote: > *But* looking at this deeper, the commit_page may need a READ_ONCE() > but not for the reason you suggested. > > commit_page = cpu_buffer->commit_page; > commit_ts = commit_page->page->time_sta

Re: [PATCH] tracefs: remove SLAB_MEM_SPREAD flag usage

On Sat, 24 Feb 2024 13:52:06 + chengming.z...@linux.dev wrote: > From: Chengming Zhou > > The SLAB_MEM_SPREAD flag is already a no-op as of 6.8-rc1, remove > its usage so we can delete it from slab. No functional change. > > Signed-off-by: Chengming Zhou Queued. Thanks! -- Steve > ---

Re: tprobe event tracing error

On Mon, 26 Feb 2024 23:41:56 +0900 Masami Hiramatsu (Google) wrote: > Hi, > (Cc: linux-kernel-trace ML for sharing this knowledge) > > On Mon, 26 Feb 2024 16:36:29 +0300 > Максим Морсков wrote: > > > > > Hello, dear Masami. > > I am researching Linux event tracing subsystem in part of

Re: [PATCH] mm: add alloc_contig_migrate_range allocation statistics

On Mon, 26 Feb 2024 12:06:29 -0500 Steven Rostedt wrote: > On Mon, 26 Feb 2024 10:00:15 + > Richard Chang wrote: > > > alloc_contig_migrate_range has every information to be able to > > understand big contiguous allocation latency. For example, how many > > p

Re: [PATCH v2] tracing: Add warning if string in __assign_str() does not match __string()

On Mon, 26 Feb 2024 09:33:28 +0900 Masami Hiramatsu (Google) wrote: > On Fri, 23 Feb 2024 16:13:56 -0500 > Steven Rostedt wrote: > > > From: "Steven Rostedt (Google)" > > > > In preparation to remove the second parameter of __assign_str(), make sure >

Re: [PATCH] mm: add alloc_contig_migrate_range allocation statistics

On Mon, 26 Feb 2024 10:00:15 + Richard Chang wrote: > alloc_contig_migrate_range has every information to be able to > understand big contiguous allocation latency. For example, how many > pages are migrated, how many times they were needed to unmap from > page tables. > > This patch adds

Re: [PATCH] ring-buffer: use READ_ONCE() to read cpu_buffer->commit_page in concurrent environment

On Sun, 25 Feb 2024 11:05:06 +0800 linke li wrote: > In function ring_buffer_iter_empty(), cpu_buffer->commit_page and > curr_commit_page->page->time_stamp is read using READ_ONCE() in > line 4354, 4355 > > 4354curr_commit_page = READ_ONCE(cpu_buffer->commit_page); > 4355curr_commit_ts

[PATCH] tracing: Remove second parameter to __assign_rel_str()

From: "Steven Rostedt (Google)" The second parameter of __assign_rel_str() is no longer used. It can be removed. Note, the only real users of rel_string is user events. This code is just in the sample code for testing purposes. This makes __assign_rel_str() different than __

[PATCH v2] tracing: Add warning if string in __assign_str() does not match __string()

From: "Steven Rostedt (Google)" In preparation to remove the second parameter of __assign_str(), make sure it is really a duplicate of __string() by adding a WARN_ON_ONCE(). Signed-off-by: Steven Rostedt (Google) --- Changes since v1: https://lore.kernel.org/linux-tr

[PATCH] tracing: Add warning if string in __assign_str() does not match __string()

From: "Steven Rostedt (Google)" In preparation to remove the second parameter of __assign_str(), make sure it is really a duplicate of __string() by adding a WARN_ON_ONCE(). Signed-off-by: Steven Rostedt (Google) --- include/trace/stages/stage6_event_callback.h | 1 + 1 file

Re: [FYI][PATCH] tracing/treewide: Remove second parameter of __assign_str()

On Fri, 23 Feb 2024 13:46:53 -0500 Steven Rostedt wrote: > Now one thing I could do is to not remove the parameter, but just add: > > WARN_ON_ONCE((src) != __data_offsets->item##_ptr_); > > in the __assign_str() macro to make sure that it's still the same that is &

[PATCH] tracing: Add __string_len() example

From: "Steven Rostedt (Google)" There's no example code that uses __string_len(), and since the sample code is used for testing the event logic, add a use case. Signed-off-by: Steven Rostedt (Google) --- samples/trace_events/trace-events-sample.h | 7 +-- 1 file changed, 5

[PATCH v2] tracing: Remove __assign_str_len()

From: "Steven Rostedt (Google)" Now that __assign_str() gets the length from the __string() (and __string_len()) macros, there's no reason to have a separate __assign_str_len() macro as __assign_str() can get the length of the string needed. Also remove __assign_rel_str() altho

Re: [FYI][PATCH] tracing/treewide: Remove second parameter of __assign_str()

On Fri, 23 Feb 2024 14:50:49 -0500 Kent Overstreet wrote: > Tangentially related though, what would make me really happy is if we > could create the string with in the TP__fast_assign() section. I have to > have a bunch of annoying wrappers right now because the string length > has to be known

[PATCH] tracing: Remove __assign_str_len()

From: "Steven Rostedt (Google)" Now that __assign_str() gets the length from the __string() (and __string_len()) macros, there's no reason to have a separate __assign_str_len() macro as __assign_str() can get the length of the string needed. Signed-off-by: Steven Rostedt (Google) --

Re: [FYI][PATCH] tracing/treewide: Remove second parameter of __assign_str()

On Fri, 23 Feb 2024 10:30:45 -0800 Jeff Johnson wrote: > On 2/23/2024 9:56 AM, Steven Rostedt wrote: > > From: "Steven Rostedt (Google)" > > > > [ > >This is a treewide change. I will likely re-create this patch again in > >the second

Re: [FYI][PATCH] tracing/treewide: Remove second parameter of __assign_str()

On Fri, 23 Feb 2024 12:56:34 -0500 Steven Rostedt wrote: > Note, the same updates will need to be done for: > > __assign_str_len() > __assign_rel_str() > __assign_rel_str_len() Correction: The below macros do not pass in their source to the entry macros, so the

[PATCH 1/2] tracing: Fix snapshot counter going between two tracers that use it

From: "Steven Rostedt (Google)" Running the ftrace selftests caused the ring buffer mapping test to fail. Investigating, I found that the snapshot counter would be incremented every time a tracer that uses the snapshot is enabled even if the snapshot was used by the previ

[PATCH 0/2] tracing: Fix snapshot accounting

The ring buffer mapping test failed after running the ftrace tests. This was due to some mismatched snapshot accounting that left the snapshot counter enabled when it was not, which prevents the ring buffer from being mapped. Steven Rostedt (Google) (2): tracing: Fix snapshot counter

[PATCH 2/2] tracing: Decrement the snapshot if the snapshot trigger fails to register

From: "Steven Rostedt (Google)" Running the ftrace selftests caused the ring buffer mapping test to fail. Investigating, I found that the snapshot counter would be incremented every time a snapshot trigger was added, even if that snapshot trigger failed. # cd /sys/kernel/traci

Re: [PATCH v4 2/4] tracing/user_events: Introduce multi-format events

On Thu, 22 Feb 2024 00:18:05 + Beau Belgrave wrote: > Currently user_events supports 1 event with the same name and must have > the exact same format when referenced by multiple programs. This opens > an opportunity for malicous or poorly thought through programs to malicious? ;-) --

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