<feed xmlns='http://www.w3.org/2005/Atom'>
<title>kernel/linux.git/include/linux/trace_events.h, branch v5.10.258</title>
<subtitle>Linux kernel stable tree (mirror)</subtitle>
<id>https://git.radix-linux.su/kernel/linux.git/atom?h=v5.10.258</id>
<link rel='self' href='https://git.radix-linux.su/kernel/linux.git/atom?h=v5.10.258'/>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/'/>
<updated>2025-10-29T13:01:15+00:00</updated>
<entry>
<title>overflow, tracing: Define the is_signed_type() macro once</title>
<updated>2025-10-29T13:01:15+00:00</updated>
<author>
<name>Bart Van Assche</name>
<email>bvanassche@acm.org</email>
</author>
<published>2025-10-17T09:04:53+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=057ebedd4eb7a40d84009ac5b8b28e7a684e4c51'/>
<id>urn:sha1:057ebedd4eb7a40d84009ac5b8b28e7a684e4c51</id>
<content type='text'>
[ Upstream commit 92d23c6e94157739b997cacce151586a0d07bb8a ]

There are two definitions of the is_signed_type() macro: one in
&lt;linux/overflow.h&gt; and a second definition in &lt;linux/trace_events.h&gt;.

As suggested by Linus Torvalds, move the definition of the
is_signed_type() macro into the &lt;linux/compiler.h&gt; header file. Change
the definition of the is_signed_type() macro to make sure that it does
not trigger any sparse warnings with future versions of sparse for
bitwise types. See also:
https://lore.kernel.org/all/CAHk-=whjH6p+qzwUdx5SOVVHjS3WvzJQr6mDUwhEyTf6pJWzaQ@mail.gmail.com/
https://lore.kernel.org/all/CAHk-=wjQGnVfb4jehFR0XyZikdQvCZouE96xR_nnf5kqaM5qqQ@mail.gmail.com/

Cc: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Cc: Arnd Bergmann &lt;arnd@arndb.de&gt;
Cc: Dan Williams &lt;dan.j.williams@intel.com&gt;
Cc: Eric Dumazet &lt;edumazet@google.com&gt;
Cc: Ingo Molnar &lt;mingo@redhat.com&gt;
Cc: Isabella Basso &lt;isabbasso@riseup.net&gt;
Cc: "Jason A. Donenfeld" &lt;Jason@zx2c4.com&gt;
Cc: Josh Poimboeuf &lt;jpoimboe@kernel.org&gt;
Cc: Luc Van Oostenryck &lt;luc.vanoostenryck@gmail.com&gt;
Cc: Masami Hiramatsu &lt;mhiramat@kernel.org&gt;
Cc: Nathan Chancellor &lt;nathan@kernel.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Rasmus Villemoes &lt;linux@rasmusvillemoes.dk&gt;
Cc: Sander Vanheule &lt;sander@svanheule.net&gt;
Cc: Steven Rostedt &lt;rostedt@goodmis.org&gt;
Cc: Vlastimil Babka &lt;vbabka@suse.cz&gt;
Cc: Yury Norov &lt;yury.norov@gmail.com&gt;
Signed-off-by: Bart Van Assche &lt;bvanassche@acm.org&gt;
Signed-off-by: Kees Cook &lt;keescook@chromium.org&gt;
Link: https://lore.kernel.org/r/20220826162116.1050972-3-bvanassche@acm.org
Signed-off-by: Eliav Farber &lt;farbere@amazon.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>tracing: Constify string literal data member in struct trace_event_call</title>
<updated>2025-01-09T12:25:00+00:00</updated>
<author>
<name>Christian Göttsche</name>
<email>cgzones@googlemail.com</email>
</author>
<published>2024-11-25T10:50:25+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=5c4a141ff09ed7d77a63e2ea604b4b7fa3644504'/>
<id>urn:sha1:5c4a141ff09ed7d77a63e2ea604b4b7fa3644504</id>
<content type='text'>
commit 452f4b31e3f70a52b97890888eeb9eaa9a87139a upstream.

The name member of the struct trace_event_call is assigned with
generated string literals; declare them pointer to read-only.

Reported by clang:

    security/landlock/syscalls.c:179:1: warning: initializing 'char *' with an expression of type 'const char[34]' discards qualifiers [-Wincompatible-pointer-types-discards-qualifiers]
      179 | SYSCALL_DEFINE3(landlock_create_ruleset,
          | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      180 |                 const struct landlock_ruleset_attr __user *const, attr,
          |                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      181 |                 const size_t, size, const __u32, flags)
          |                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    ./include/linux/syscalls.h:226:36: note: expanded from macro 'SYSCALL_DEFINE3'
      226 | #define SYSCALL_DEFINE3(name, ...) SYSCALL_DEFINEx(3, _##name, __VA_ARGS__)
          |                                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    ./include/linux/syscalls.h:234:2: note: expanded from macro 'SYSCALL_DEFINEx'
      234 |         SYSCALL_METADATA(sname, x, __VA_ARGS__)                 \
          |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    ./include/linux/syscalls.h:184:2: note: expanded from macro 'SYSCALL_METADATA'
      184 |         SYSCALL_TRACE_ENTER_EVENT(sname);                       \
          |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    ./include/linux/syscalls.h:151:30: note: expanded from macro 'SYSCALL_TRACE_ENTER_EVENT'
      151 |                         .name                   = "sys_enter"#sname,    \
          |                                                   ^~~~~~~~~~~~~~~~~

Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu &lt;mhiramat@kernel.org&gt;
Cc: Mathieu Desnoyers &lt;mathieu.desnoyers@efficios.com&gt;
Cc: Mickaël Salaün &lt;mic@digikod.net&gt;
Cc: Günther Noack &lt;gnoack@google.com&gt;
Cc: Nathan Chancellor &lt;nathan@kernel.org&gt;
Cc: Nick Desaulniers &lt;ndesaulniers@google.com&gt;
Cc: Bill Wendling &lt;morbo@google.com&gt;
Cc: Justin Stitt &lt;justinstitt@google.com&gt;
Link: https://lore.kernel.org/20241125105028.42807-1-cgoettsche@seltendoof.de
Fixes: b77e38aa240c3 ("tracing: add event trace infrastructure")
Signed-off-by: Christian Göttsche &lt;cgzones@googlemail.com&gt;
Signed-off-by: Steven Rostedt (Google) &lt;rostedt@goodmis.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>bpf: kprobe: remove unused declaring of bpf_kprobe_override</title>
<updated>2024-08-19T03:41:16+00:00</updated>
<author>
<name>Menglong Dong</name>
<email>menglong8.dong@gmail.com</email>
</author>
<published>2024-08-05T05:01:21+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=9ddd5e7835c66c64cd007d9300a2fe7ab64ea554'/>
<id>urn:sha1:9ddd5e7835c66c64cd007d9300a2fe7ab64ea554</id>
<content type='text'>
[ Upstream commit 0e8b53979ac86eddb3fd76264025a70071a25574 ]

After the commit 66665ad2f102 ("tracing/kprobe: bpf: Compare instruction
pointer with original one"), "bpf_kprobe_override" is not used anywhere
anymore, and we can remove it now.

Link: https://lore.kernel.org/all/20240710085939.11520-1-dongml2@chinatelecom.cn/

Fixes: 66665ad2f102 ("tracing/kprobe: bpf: Compare instruction pointer with original one")
Signed-off-by: Menglong Dong &lt;dongml2@chinatelecom.cn&gt;
Acked-by: Jiri Olsa &lt;jolsa@kernel.org&gt;
Signed-off-by: Masami Hiramatsu (Google) &lt;mhiramat@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>tracing: Increase PERF_MAX_TRACE_SIZE to handle Sentinel1 and docker together</title>
<updated>2024-05-02T14:23:43+00:00</updated>
<author>
<name>Robin H. Johnson</name>
<email>robbat2@gentoo.org</email>
</author>
<published>2021-08-31T04:37:23+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=772a23d60a642ff65021b00504ce43b04cb86b15'/>
<id>urn:sha1:772a23d60a642ff65021b00504ce43b04cb86b15</id>
<content type='text'>
commit e531e90b5ab0f7ce5ff298e165214c1aec6ed187 upstream.

Running endpoint security solutions like Sentinel1 that use perf-based
tracing heavily lead to this repeated dump complaining about dockerd.
The default value of 2048 is nowhere near not large enough.

Using the prior patch "tracing: show size of requested buffer", we get
"perf buffer not large enough, wanted 6644, have 6144", after repeated
up-sizing (I did 2/4/6/8K). With 8K, the problem doesn't occur at all,
so below is the trace for 6K.

I'm wondering if this value should be selectable at boot time, but this
is a good starting point.

```
------------[ cut here ]------------
perf buffer not large enough, wanted 6644, have 6144
WARNING: CPU: 1 PID: 4997 at kernel/trace/trace_event_perf.c:402 perf_trace_buf_alloc+0x8c/0xa0
Modules linked in: [..]
CPU: 1 PID: 4997 Comm: sh Tainted: G                T 5.13.13-x86_64-00039-gb3959163488e #63
Hardware name: LENOVO 20KH002JUS/20KH002JUS, BIOS N23ET66W (1.41 ) 09/02/2019
RIP: 0010:perf_trace_buf_alloc+0x8c/0xa0
Code: 80 3d 43 97 d0 01 00 74 07 31 c0 5b 5d 41 5c c3 ba 00 18 00 00 89 ee 48 c7 c7 00 82 7d 91 c6 05 25 97 d0 01 01 e8 22 ee bc 00 &lt;0f&gt; 0b 31 c0 eb db 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 55 89
RSP: 0018:ffffb922026b7d58 EFLAGS: 00010282
RAX: 0000000000000000 RBX: ffff9da5ee012000 RCX: 0000000000000027
RDX: ffff9da881657828 RSI: 0000000000000001 RDI: ffff9da881657820
RBP: 00000000000019f4 R08: 0000000000000000 R09: ffffb922026b7b80
R10: ffffb922026b7b78 R11: ffffffff91dda688 R12: 000000000000000f
R13: ffff9da5ee012108 R14: ffff9da8816570a0 R15: ffffb922026b7e30
FS:  00007f420db1a080(0000) GS:ffff9da881640000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000060 CR3: 00000002504a8006 CR4: 00000000003706e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 kprobe_perf_func+0x11e/0x270
 ? do_execveat_common.isra.0+0x1/0x1c0
 ? do_execveat_common.isra.0+0x5/0x1c0
 kprobe_ftrace_handler+0x10e/0x1d0
 0xffffffffc03aa0c8
 ? do_execveat_common.isra.0+0x1/0x1c0
 do_execveat_common.isra.0+0x5/0x1c0
 __x64_sys_execve+0x33/0x40
 do_syscall_64+0x6b/0xc0
 ? do_syscall_64+0x11/0xc0
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f420dc1db37
Code: ff ff 76 e7 f7 d8 64 41 89 00 eb df 0f 1f 80 00 00 00 00 f7 d8 64 41 89 00 eb dc 0f 1f 84 00 00 00 00 00 b8 3b 00 00 00 0f 05 &lt;48&gt; 3d 01 f0 ff ff 73 01 c3 48 8b 0d 01 43 0f 00 f7 d8 64 89 01 48
RSP: 002b:00007ffd4e8b4e38 EFLAGS: 00000246 ORIG_RAX: 000000000000003b
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f420dc1db37
RDX: 0000564338d1e740 RSI: 0000564338d32d50 RDI: 0000564338d28f00
RBP: 0000564338d28f00 R08: 0000564338d32d50 R09: 0000000000000020
R10: 00000000000001b6 R11: 0000000000000246 R12: 0000564338d28f00
R13: 0000564338d32d50 R14: 0000564338d1e740 R15: 0000564338d28c60
---[ end trace 83ab3e8e16275e49 ]---
```

Link: https://lkml.kernel.org/r/20210831043723.13481-2-robbat2@gentoo.org

Signed-off-by: Robin H. Johnson &lt;robbat2@gentoo.org&gt;
Signed-off-by: Steven Rostedt (VMware) &lt;rostedt@goodmis.org&gt;
Signed-off-by: Thadeu Lima de Souza Cascardo &lt;cascardo@igalia.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>tracing: Have trace_event_file have ref counters</title>
<updated>2023-11-28T16:55:02+00:00</updated>
<author>
<name>Steven Rostedt (Google)</name>
<email>rostedt@goodmis.org</email>
</author>
<published>2023-10-31T16:24:53+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=a98172e36e5f1b3d29ad71fade2d611cfcc2fe6f'/>
<id>urn:sha1:a98172e36e5f1b3d29ad71fade2d611cfcc2fe6f</id>
<content type='text'>
commit bb32500fb9b78215e4ef6ee8b4345c5f5d7eafb4 upstream.

The following can crash the kernel:

 # cd /sys/kernel/tracing
 # echo 'p:sched schedule' &gt; kprobe_events
 # exec 5&gt;&gt;events/kprobes/sched/enable
 # &gt; kprobe_events
 # exec 5&gt;&amp;-

The above commands:

 1. Change directory to the tracefs directory
 2. Create a kprobe event (doesn't matter what one)
 3. Open bash file descriptor 5 on the enable file of the kprobe event
 4. Delete the kprobe event (removes the files too)
 5. Close the bash file descriptor 5

The above causes a crash!

 BUG: kernel NULL pointer dereference, address: 0000000000000028
 #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: 6 PID: 877 Comm: bash Not tainted 6.5.0-rc4-test-00008-g2c6b6b1029d4-dirty #186
 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
 RIP: 0010:tracing_release_file_tr+0xc/0x50

What happens here is that the kprobe event creates a trace_event_file
"file" descriptor that represents the file in tracefs to the event. It
maintains state of the event (is it enabled for the given instance?).
Opening the "enable" file gets a reference to the event "file" descriptor
via the open file descriptor. When the kprobe event is deleted, the file is
also deleted from the tracefs system which also frees the event "file"
descriptor.

But as the tracefs file is still opened by user space, it will not be
totally removed until the final dput() is called on it. But this is not
true with the event "file" descriptor that is already freed. If the user
does a write to or simply closes the file descriptor it will reference the
event "file" descriptor that was just freed, causing a use-after-free bug.

To solve this, add a ref count to the event "file" descriptor as well as a
new flag called "FREED". The "file" will not be freed until the last
reference is released. But the FREE flag will be set when the event is
removed to prevent any more modifications to that event from happening,
even if there's still a reference to the event "file" descriptor.

Link: https://lore.kernel.org/linux-trace-kernel/20231031000031.1e705592@gandalf.local.home/
Link: https://lore.kernel.org/linux-trace-kernel/20231031122453.7a48b923@gandalf.local.home

Cc: stable@vger.kernel.org
Cc: Mark Rutland &lt;mark.rutland@arm.com&gt;
Fixes: f5ca233e2e66d ("tracing: Increase trace array ref count on enable and filter files")
Reported-by: Beau Belgrave &lt;beaub@linux.microsoft.com&gt;
Tested-by: Beau Belgrave &lt;beaub@linux.microsoft.com&gt;
Reviewed-by: Masami Hiramatsu (Google) &lt;mhiramat@kernel.org&gt;
Signed-off-by: Steven Rostedt (Google) &lt;rostedt@goodmis.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>bpf: Clear the probe_addr for uprobe</title>
<updated>2023-09-19T10:20:07+00:00</updated>
<author>
<name>Yafang Shao</name>
<email>laoar.shao@gmail.com</email>
</author>
<published>2023-07-09T02:56:25+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=b275f0ae3598936e37b2cd3b0e862dc40e27be00'/>
<id>urn:sha1:b275f0ae3598936e37b2cd3b0e862dc40e27be00</id>
<content type='text'>
[ Upstream commit 5125e757e62f6c1d5478db4c2b61a744060ddf3f ]

To avoid returning uninitialized or random values when querying the file
descriptor (fd) and accessing probe_addr, it is necessary to clear the
variable prior to its use.

Fixes: 41bdc4b40ed6 ("bpf: introduce bpf subcommand BPF_TASK_FD_QUERY")
Signed-off-by: Yafang Shao &lt;laoar.shao@gmail.com&gt;
Acked-by: Yonghong Song &lt;yhs@fb.com&gt;
Acked-by: Jiri Olsa &lt;jolsa@kernel.org&gt;
Link: https://lore.kernel.org/r/20230709025630.3735-6-laoar.shao@gmail.com
Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>tracing: Show real address for trace event arguments</title>
<updated>2023-08-11T09:57:33+00:00</updated>
<author>
<name>Masami Hiramatsu</name>
<email>mhiramat@kernel.org</email>
</author>
<published>2020-10-15T14:55:07+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=840ce9cfc86f89c335625ec297acc0375f82e19b'/>
<id>urn:sha1:840ce9cfc86f89c335625ec297acc0375f82e19b</id>
<content type='text'>
[ Upstream commit efbbdaa22bb78761bff8dfdde027ad04bedd47ce ]

To help debugging kernel, show real address for trace event arguments
in tracefs/trace{,pipe} instead of hashed pointer value.

Since ftrace human-readable format uses vsprintf(), all %p are
translated to hash values instead of pointer address.

However, when debugging the kernel, raw address value gives a
hint when comparing with the memory mapping in the kernel.
(Those are sometimes used with crash log, which is not hashed too)
So converting %p with %px when calling trace_seq_printf().

Moreover, this is not improving the security because the tracefs
can be used only by root user and the raw address values are readable
from tracefs/percpu/cpu*/trace_pipe_raw file.

Link: https://lkml.kernel.org/r/160277370703.29307.5134475491761971203.stgit@devnote2

Signed-off-by: Masami Hiramatsu &lt;mhiramat@kernel.org&gt;
Signed-off-by: Steven Rostedt (VMware) &lt;rostedt@goodmis.org&gt;
Stable-dep-of: d5a821896360 ("tracing: Fix memory leak of iter-&gt;temp when reading trace_pipe")
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>tracing: Add length protection to histogram string copies</title>
<updated>2021-11-26T09:39:14+00:00</updated>
<author>
<name>Steven Rostedt (VMware)</name>
<email>rostedt@goodmis.org</email>
</author>
<published>2021-11-14T18:28:34+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=3984876f91a3da423fa27c3f48b568a58f4a65d8'/>
<id>urn:sha1:3984876f91a3da423fa27c3f48b568a58f4a65d8</id>
<content type='text'>
[ Upstream commit 938aa33f14657c9ed9deea348b7d6f14b6d69cb7 ]

The string copies to the histogram storage has a max size of 256 bytes
(defined by MAX_FILTER_STR_VAL). Only the string size of the event field
needs to be copied to the event storage, but no more than what is in the
event storage. Although nothing should be bigger than 256 bytes, there's
no protection against overwriting of the storage if one day there is.

Copy no more than the destination size, and enforce it.

Also had to turn MAX_FILTER_STR_VAL into an unsigned int, to keep the
min() comparison of the string sizes of comparable types.

Link: https://lore.kernel.org/all/CAHk-=wjREUihCGrtRBwfX47y_KrLCGjiq3t6QtoNJpmVrAEb1w@mail.gmail.com/
Link: https://lkml.kernel.org/r/20211114132834.183429a4@rorschach.local.home

Cc: Ingo Molnar &lt;mingo@kernel.org&gt;
Cc: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Cc: Tom Zanussi &lt;zanussi@kernel.org&gt;
Reported-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Reviewed-by: Masami Hiramatsu &lt;mhiramat@kernel.org&gt;
Fixes: 63f84ae6b82b ("tracing/histogram: Do not copy the fixed-size char array field over the field size")
Signed-off-by: Steven Rostedt (VMware) &lt;rostedt@goodmis.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>treewide: Convert macro and uses of __section(foo) to __section("foo")</title>
<updated>2020-10-25T21:51:49+00:00</updated>
<author>
<name>Joe Perches</name>
<email>joe@perches.com</email>
</author>
<published>2020-10-22T02:36:07+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=33def8498fdde180023444b08e12b72a9efed41d'/>
<id>urn:sha1:33def8498fdde180023444b08e12b72a9efed41d</id>
<content type='text'>
Use a more generic form for __section that requires quotes to avoid
complications with clang and gcc differences.

Remove the quote operator # from compiler_attributes.h __section macro.

Convert all unquoted __section(foo) uses to quoted __section("foo").
Also convert __attribute__((section("foo"))) uses to __section("foo")
even if the __attribute__ has multiple list entry forms.

Conversion done using the script at:

    https://lore.kernel.org/lkml/75393e5ddc272dc7403de74d645e6c6e0f4e70eb.camel@perches.com/2-convert_section.pl

Signed-off-by: Joe Perches &lt;joe@perches.com&gt;
Reviewed-by: Nick Desaulniers &lt;ndesaulniers@gooogle.com&gt;
Reviewed-by: Miguel Ojeda &lt;ojeda@kernel.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>tracing: Save off entry when peeking at next entry</title>
<updated>2020-03-19T21:48:36+00:00</updated>
<author>
<name>Steven Rostedt (VMware)</name>
<email>rostedt@goodmis.org</email>
</author>
<published>2020-03-17T21:32:23+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=ff895103a84abc85a5f43ecabc7f67cf36e1348f'/>
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In order to have the iterator read the buffer even when it's still updating,
it requires that the ring buffer iterator saves each event in a separate
location outside the ring buffer such that its use is immutable.

There's one use case that saves off the event returned from the ring buffer
interator and calls it again to look at the next event, before going back to
use the first event. As the ring buffer iterator will only have a single
copy, this use case will no longer be supported.

Instead, have the one use case create its own buffer to store the first
event when looking at the next event. This way, when looking at the first
event again, it wont be corrupted by the second read.

Link: http://lkml.kernel.org/r/20200317213415.722539921@goodmis.org

Signed-off-by: Steven Rostedt (VMware) &lt;rostedt@goodmis.org&gt;
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