user/sven/linux.git/kernel/trace, branch v5.10.152

tracing: Do not free snapshot if tracer is on cmdline

2022-10-30T08:41:18Z

[ Upstream commit a541a9559bb0a8ecc434de01d3e4826c32e8bb53 ] The ftrace_boot_snapshot and alloc_snapshot cmdline options allocate the snapshot buffer at boot up for use later. The ftrace_boot_snapshot in particular requires the snapshot to be allocated because it will take a snapshot at the end of boot up allowing to see the traces that happened during boot so that it's not lost when user space takes over. When a tracer is registered (started) there's a path that checks if it requires the snapshot buffer or not, and if it does not and it was allocated it will do a synchronization and free the snapshot buffer. This is only required if the previous tracer was using it for "max latency" snapshots, as it needs to make sure all max snapshots are complete before freeing. But this is only needed if the previous tracer was using the snapshot buffer for latency (like irqoff tracer and friends). But it does not make sense to free it, if the previous tracer was not using it, and the snapshot was allocated by the cmdline parameters. This basically takes away the point of allocating it in the first place! Note, the allocated snapshot worked fine for just trace events, but fails when a tracer is enabled on the cmdline. Further investigation, this goes back even further and it does not require a tracer on the cmdline to fail. Simply enable snapshots and then enable a tracer, and it will remove the snapshot. Link: https://lkml.kernel.org/r/20221005113757.041df7fe@gandalf.local.home Cc: Masami Hiramatsu Cc: Andrew Morton Cc: stable@vger.kernel.org Fixes: 45ad21ca5530 ("tracing: Have trace_array keep track if snapshot buffer is allocated") Reported-by: Ross Zwisler Tested-by: Ross Zwisler Signed-off-by: Steven Rostedt (Google) Signed-off-by: Sasha Levin

tracing: Simplify conditional compilation code in tracing_set_tracer()

2022-10-30T08:41:18Z

[ Upstream commit f4b0d318097e45cbac5e14976f8bb56aa2cef504 ] Two conditional compilation directives "#ifdef CONFIG_TRACER_MAX_TRACE" are used consecutively, and no other code in between. Simplify conditional the compilation code and only use one "#ifdef CONFIG_TRACER_MAX_TRACE". Link: https://lkml.kernel.org/r/20220602140613.545069-1-sunliming@kylinos.cn Signed-off-by: sunliming Signed-off-by: Steven Rostedt (Google) Stable-dep-of: a541a9559bb0 ("tracing: Do not free snapshot if tracer is on cmdline") Signed-off-by: Sasha Levin

tracing: kprobe: Make gen test module work in arm and riscv

2022-10-26T11:25:43Z

[ Upstream commit d8ef45d66c01425ff748e13ef7dd1da7a91cc93c ] For now, this selftest module can only work in x86 because of the kprobe cmd was fixed use of x86 registers. This patch adapted to register names under arm and riscv, So that this module can be worked on those platform. Link: https://lkml.kernel.org/r/20220919125629.238242-3-zouyipeng@huawei.com Cc: Cc: Cc: Cc: Cc: Cc: Cc: Cc: Fixes: 64836248dda2 ("tracing: Add kprobe event command generation test module") Signed-off-by: Yipeng Zou Acked-by: Masami Hiramatsu (Google) Signed-off-by: Steven Rostedt (Google) Signed-off-by: Sasha Levin

tracing: kprobe: Fix kprobe event gen test module on exit

2022-10-26T11:25:42Z

[ Upstream commit ac48e189527fae87253ef2bf58892e782fb36874 ] Correct gen_kretprobe_test clr event para on module exit. This will make it can't to delete. Link: https://lkml.kernel.org/r/20220919125629.238242-2-zouyipeng@huawei.com Cc: Cc: Cc: Cc: Cc: Cc: Cc: Cc: Fixes: 64836248dda2 ("tracing: Add kprobe event command generation test module") Signed-off-by: Yipeng Zou Acked-by: Masami Hiramatsu (Google) Signed-off-by: Steven Rostedt (Google) Signed-off-by: Sasha Levin

tracing: Disable interrupt or preemption before acquiring arch_spinlock_t

2022-10-26T11:25:15Z

commit c0a581d7126c0bbc96163276f585fd7b4e4d8d0e upstream. It was found that some tracing functions in kernel/trace/trace.c acquire an arch_spinlock_t with preemption and irqs enabled. An example is the tracing_saved_cmdlines_size_read() function which intermittently causes a "BUG: using smp_processor_id() in preemptible" warning when the LTP read_all_proc test is run. That can be problematic in case preemption happens after acquiring the lock. Add the necessary preemption or interrupt disabling code in the appropriate places before acquiring an arch_spinlock_t. The convention here is to disable preemption for trace_cmdline_lock and interupt for max_lock. Link: https://lkml.kernel.org/r/20220922145622.1744826-1-longman@redhat.com Cc: Peter Zijlstra Cc: Ingo Molnar Cc: Will Deacon Cc: Boqun Feng Cc: stable@vger.kernel.org Fixes: a35873a0993b ("tracing: Add conditional snapshot") Fixes: 939c7a4f04fc ("tracing: Introduce saved_cmdlines_size file") Suggested-by: Steven Rostedt Signed-off-by: Waiman Long Signed-off-by: Steven Rostedt (Google) Signed-off-by: Greg Kroah-Hartman

ring-buffer: Fix race between reset page and reading page

2022-10-26T11:25:15Z

commit a0fcaaed0c46cf9399d3a2d6e0c87ddb3df0e044 upstream. The ring buffer is broken up into sub buffers (currently of page size). Each sub buffer has a pointer to its "tail" (the last event written to the sub buffer). When a new event is requested, the tail is locally incremented to cover the size of the new event. This is done in a way that there is no need for locking. If the tail goes past the end of the sub buffer, the process of moving to the next sub buffer takes place. After setting the current sub buffer to the next one, the previous one that had the tail go passed the end of the sub buffer needs to be reset back to the original tail location (before the new event was requested) and the rest of the sub buffer needs to be "padded". The race happens when a reader takes control of the sub buffer. As readers do a "swap" of sub buffers from the ring buffer to get exclusive access to the sub buffer, it replaces the "head" sub buffer with an empty sub buffer that goes back into the writable portion of the ring buffer. This swap can happen as soon as the writer moves to the next sub buffer and before it updates the last sub buffer with padding. Because the sub buffer can be released to the reader while the writer is still updating the padding, it is possible for the reader to see the event that goes past the end of the sub buffer. This can cause obvious issues. To fix this, add a few memory barriers so that the reader definitely sees the updates to the sub buffer, and also waits until the writer has put back the "tail" of the sub buffer back to the last event that was written on it. To be paranoid, it will only spin for 1 second, otherwise it will warn and shutdown the ring buffer code. 1 second should be enough as the writer does have preemption disabled. If the writer doesn't move within 1 second (with preemption disabled) something is horribly wrong. No interrupt should last 1 second! Link: https://lore.kernel.org/all/20220830120854.7545-1-jiazi.li@transsion.com/ Link: https://bugzilla.kernel.org/show_bug.cgi?id=216369 Link: https://lkml.kernel.org/r/20220929104909.0650a36c@gandalf.local.home Cc: Ingo Molnar Cc: Andrew Morton Cc: stable@vger.kernel.org Fixes: c7b0930857e22 ("ring-buffer: prevent adding write in discarded area") Reported-by: Jiazi.Li Signed-off-by: Steven Rostedt (Google) Signed-off-by: Greg Kroah-Hartman

ring-buffer: Add ring_buffer_wake_waiters()

2022-10-26T11:25:15Z

commit 7e9fbbb1b776d8d7969551565bc246f74ec53b27 upstream. On closing of a file that represents a ring buffer or flushing the file, there may be waiters on the ring buffer that needs to be woken up and exit the ring_buffer_wait() function. Add ring_buffer_wake_waiters() to wake up the waiters on the ring buffer and allow them to exit the wait loop. Link: https://lkml.kernel.org/r/20220928133938.28dc2c27@gandalf.local.home Cc: stable@vger.kernel.org Cc: Ingo Molnar Cc: Andrew Morton Fixes: 15693458c4bc0 ("tracing/ring-buffer: Move poll wake ups into ring buffer code") Signed-off-by: Steven Rostedt (Google) Signed-off-by: Greg Kroah-Hartman

ring-buffer: Check pending waiters when doing wake ups as well

2022-10-26T11:25:15Z

commit ec0bbc5ec5664dcee344f79373852117dc672c86 upstream. The wake up waiters only checks the "wakeup_full" variable and not the "full_waiters_pending". The full_waiters_pending is set when a waiter is added to the wait queue. The wakeup_full is only set when an event is triggered, and it clears the full_waiters_pending to avoid multiple calls to irq_work_queue(). The irq_work callback really needs to check both wakeup_full as well as full_waiters_pending such that this code can be used to wake up waiters when a file is closed that represents the ring buffer and the waiters need to be woken up. Link: https://lkml.kernel.org/r/20220927231824.209460321@goodmis.org Cc: stable@vger.kernel.org Cc: Ingo Molnar Cc: Andrew Morton Fixes: 15693458c4bc0 ("tracing/ring-buffer: Move poll wake ups into ring buffer code") Signed-off-by: Steven Rostedt (Google) Signed-off-by: Greg Kroah-Hartman

ring-buffer: Have the shortest_full queue be the shortest not longest

2022-10-26T11:25:15Z

commit 3b19d614b61b93a131f463817e08219c9ce1fee3 upstream. The logic to know when the shortest waiters on the ring buffer should be woken up or not has uses a less than instead of a greater than compare, which causes the shortest_full to actually be the longest. Link: https://lkml.kernel.org/r/20220927231823.718039222@goodmis.org Cc: stable@vger.kernel.org Cc: Ingo Molnar Cc: Andrew Morton Fixes: 2c2b0a78b3739 ("ring-buffer: Add percentage of ring buffer full to wake up reader") Signed-off-by: Steven Rostedt (Google) Signed-off-by: Greg Kroah-Hartman

ring-buffer: Allow splice to read previous partially read pages

2022-10-26T11:25:14Z

commit fa8f4a89736b654125fb254b0db753ac68a5fced upstream. If a page is partially read, and then the splice system call is run against the ring buffer, it will always fail to read, no matter how much is in the ring buffer. That's because the code path for a partial read of the page does will fail if the "full" flag is set. The splice system call wants full pages, so if the read of the ring buffer is not yet full, it should return zero, and the splice will block. But if a previous read was done, where the beginning has been consumed, it should still be given to the splice caller if the rest of the page has been written to. This caused the splice command to never consume data in this scenario, and let the ring buffer just fill up and lose events. Link: https://lkml.kernel.org/r/20220927144317.46be6b80@gandalf.local.home Cc: stable@vger.kernel.org Fixes: 8789a9e7df6bf ("ring-buffer: read page interface") Signed-off-by: Steven Rostedt (Google) Signed-off-by: Greg Kroah-Hartman