* Re: [trace:ftrace/core 29/38] kernel/trace/trace.c:3232:6: warning: variable 'buffer' is used uninitialized whenever 'if' condition is true
[not found] <202001230452.x1ZgvXCx%lkp@intel.com>
@ 2020-01-22 22:02 ` Nick Desaulniers
2020-01-23 2:06 ` Steven Rostedt
0 siblings, 1 reply; 2+ messages in thread
From: Nick Desaulniers @ 2020-01-22 22:02 UTC (permalink / raw)
To: kbuild-all
[-- Attachment #1: Type: text/plain, Size: 9239 bytes --]
+Steven, looks legit, can you please take a look?
On Wed, Jan 22, 2020 at 12:40 PM kbuild test robot <lkp@intel.com> wrote:
>
> CC: kbuild-all(a)lists.01.org
> TO: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
>
> tree: https://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git ftrace/core
> head: 532f49a6f19a153e202b5a174f8556fd50c36dd4
> commit: 82d1b8158c9a77c2c9b04c4af22fd62f3686cd9d [29/38] tracing: Allow trace_printk() to nest in other tracing code
> config: x86_64-defconfig (attached as .config)
> compiler: clang version 11.0.0 (git://gitmirror/llvm_project 7b771ed448487705237868f705da17b40c6bfe82)
> reproduce:
> git checkout 82d1b8158c9a77c2c9b04c4af22fd62f3686cd9d
> # save the attached .config to linux build tree
> make ARCH=x86_64
>
> If you fix the issue, kindly add following tag
> Reported-by: kbuild test robot <lkp@intel.com>
>
> All warnings (new ones prefixed by >>):
>
> >> kernel/trace/trace.c:3232:6: warning: variable 'buffer' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized]
> if (len > TRACE_BUF_SIZE/sizeof(int) || len < 0)
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> kernel/trace/trace.c:3254:23: note: uninitialized use occurs here
> ring_buffer_nest_end(buffer);
> ^~~~~~
> kernel/trace/trace.c:3232:2: note: remove the 'if' if its condition is always false
> if (len > TRACE_BUF_SIZE/sizeof(int) || len < 0)
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >> kernel/trace/trace.c:3232:6: warning: variable 'buffer' is used uninitialized whenever '||' condition is true [-Wsometimes-uninitialized]
> if (len > TRACE_BUF_SIZE/sizeof(int) || len < 0)
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> kernel/trace/trace.c:3254:23: note: uninitialized use occurs here
> ring_buffer_nest_end(buffer);
> ^~~~~~
> kernel/trace/trace.c:3232:6: note: remove the '||' if its condition is always false
> if (len > TRACE_BUF_SIZE/sizeof(int) || len < 0)
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> kernel/trace/trace.c:3208:29: note: initialize the variable 'buffer' to silence this warning
> struct trace_buffer *buffer;
> ^
> = NULL
> 2 warnings generated.
>
> vim +3232 kernel/trace/trace.c
>
> 07d777fe8c3985 Steven Rostedt 2011-09-22 3197
> 769b0441f438c4 Frederic Weisbecker 2009-03-06 3198 /**
> 48ead02030f849 Frederic Weisbecker 2009-03-12 3199 * trace_vbprintk - write binary msg to tracing buffer
> c68c9ec1c52e5b Jakub Kicinski 2019-08-27 3200 * @ip: The address of the caller
> c68c9ec1c52e5b Jakub Kicinski 2019-08-27 3201 * @fmt: The string format to write to the buffer
> c68c9ec1c52e5b Jakub Kicinski 2019-08-27 3202 * @args: Arguments for @fmt
> 769b0441f438c4 Frederic Weisbecker 2009-03-06 3203 */
> 40ce74f19c2807 Steven Rostedt 2009-03-19 3204 int trace_vbprintk(unsigned long ip, const char *fmt, va_list args)
> 769b0441f438c4 Frederic Weisbecker 2009-03-06 3205 {
> 2425bcb9240f8c Steven Rostedt (Red Hat 2015-05-05 3206) struct trace_event_call *call = &event_bprint;
> 769b0441f438c4 Frederic Weisbecker 2009-03-06 3207 struct ring_buffer_event *event;
> 13292494379f92 Steven Rostedt (VMware 2019-12-13 3208) struct trace_buffer *buffer;
> 769b0441f438c4 Frederic Weisbecker 2009-03-06 3209 struct trace_array *tr = &global_trace;
> 48ead02030f849 Frederic Weisbecker 2009-03-12 3210 struct bprint_entry *entry;
> 769b0441f438c4 Frederic Weisbecker 2009-03-06 3211 unsigned long flags;
> 07d777fe8c3985 Steven Rostedt 2011-09-22 3212 char *tbuffer;
> 07d777fe8c3985 Steven Rostedt 2011-09-22 3213 int len = 0, size, pc;
> 769b0441f438c4 Frederic Weisbecker 2009-03-06 3214
> 769b0441f438c4 Frederic Weisbecker 2009-03-06 3215 if (unlikely(tracing_selftest_running || tracing_disabled))
> 769b0441f438c4 Frederic Weisbecker 2009-03-06 3216 return 0;
> 769b0441f438c4 Frederic Weisbecker 2009-03-06 3217
> 769b0441f438c4 Frederic Weisbecker 2009-03-06 3218 /* Don't pollute graph traces with trace_vprintk internals */
> 769b0441f438c4 Frederic Weisbecker 2009-03-06 3219 pause_graph_tracing();
> 769b0441f438c4 Frederic Weisbecker 2009-03-06 3220
> 769b0441f438c4 Frederic Weisbecker 2009-03-06 3221 pc = preempt_count();
> 5168ae50a66e3f Steven Rostedt 2010-06-03 3222 preempt_disable_notrace();
> 769b0441f438c4 Frederic Weisbecker 2009-03-06 3223
> 07d777fe8c3985 Steven Rostedt 2011-09-22 3224 tbuffer = get_trace_buf();
> 07d777fe8c3985 Steven Rostedt 2011-09-22 3225 if (!tbuffer) {
> 07d777fe8c3985 Steven Rostedt 2011-09-22 3226 len = 0;
> e2ace001176dc9 Andy Lutomirski 2016-05-26 3227 goto out_nobuffer;
> 07d777fe8c3985 Steven Rostedt 2011-09-22 3228 }
> 769b0441f438c4 Frederic Weisbecker 2009-03-06 3229
> 07d777fe8c3985 Steven Rostedt 2011-09-22 3230 len = vbin_printf((u32 *)tbuffer, TRACE_BUF_SIZE/sizeof(int), fmt, args);
> 769b0441f438c4 Frederic Weisbecker 2009-03-06 3231
> 07d777fe8c3985 Steven Rostedt 2011-09-22 @3232 if (len > TRACE_BUF_SIZE/sizeof(int) || len < 0)
> 07d777fe8c3985 Steven Rostedt 2011-09-22 3233 goto out;
^ should probably `goto out_nobuffer;` unless `put_trace_buf()` needs
to be called. Maybe there's another label needed?
> 769b0441f438c4 Frederic Weisbecker 2009-03-06 3234
> 07d777fe8c3985 Steven Rostedt 2011-09-22 3235 local_save_flags(flags);
> 769b0441f438c4 Frederic Weisbecker 2009-03-06 3236 size = sizeof(*entry) + sizeof(u32) * len;
> 1c5eb4481e0151 Steven Rostedt (VMware 2020-01-09 3237) buffer = tr->array_buffer.buffer;
> 82d1b8158c9a77 Steven Rostedt (VMware 2020-01-16 3238) ring_buffer_nest_start(buffer);
> 3e9a8aadca4807 Steven Rostedt (Red Hat 2016-11-23 3239) event = __trace_buffer_lock_reserve(buffer, TRACE_BPRINT, size,
> e77405ad80f539 Steven Rostedt 2009-09-02 3240 flags, pc);
> 769b0441f438c4 Frederic Weisbecker 2009-03-06 3241 if (!event)
> 07d777fe8c3985 Steven Rostedt 2011-09-22 3242 goto out;
> 769b0441f438c4 Frederic Weisbecker 2009-03-06 3243 entry = ring_buffer_event_data(event);
> 769b0441f438c4 Frederic Weisbecker 2009-03-06 3244 entry->ip = ip;
> 769b0441f438c4 Frederic Weisbecker 2009-03-06 3245 entry->fmt = fmt;
> 769b0441f438c4 Frederic Weisbecker 2009-03-06 3246
> 07d777fe8c3985 Steven Rostedt 2011-09-22 3247 memcpy(entry->buf, tbuffer, sizeof(u32) * len);
> f306cc82a93d6b Tom Zanussi 2013-10-24 3248 if (!call_filter_check_discard(call, entry, buffer, event)) {
> 7ffbd48d5cab22 Steven Rostedt 2012-10-11 3249 __buffer_unlock_commit(buffer, event);
> 2d34f48955158c Steven Rostedt (Red Hat 2015-09-30 3250) ftrace_trace_stack(tr, buffer, flags, 6, pc, NULL);
> d931369b74b3d6 Steven Rostedt 2010-01-06 3251 }
> 769b0441f438c4 Frederic Weisbecker 2009-03-06 3252
> 769b0441f438c4 Frederic Weisbecker 2009-03-06 3253 out:
> 82d1b8158c9a77 Steven Rostedt (VMware 2020-01-16 3254) ring_buffer_nest_end(buffer);
> e2ace001176dc9 Andy Lutomirski 2016-05-26 3255 put_trace_buf();
> e2ace001176dc9 Andy Lutomirski 2016-05-26 3256
> e2ace001176dc9 Andy Lutomirski 2016-05-26 3257 out_nobuffer:
> 5168ae50a66e3f Steven Rostedt 2010-06-03 3258 preempt_enable_notrace();
> 769b0441f438c4 Frederic Weisbecker 2009-03-06 3259 unpause_graph_tracing();
> 769b0441f438c4 Frederic Weisbecker 2009-03-06 3260
> 769b0441f438c4 Frederic Weisbecker 2009-03-06 3261 return len;
> 769b0441f438c4 Frederic Weisbecker 2009-03-06 3262 }
> 48ead02030f849 Frederic Weisbecker 2009-03-12 3263 EXPORT_SYMBOL_GPL(trace_vbprintk);
> 48ead02030f849 Frederic Weisbecker 2009-03-12 3264
>
> :::::: The code at line 3232 was first introduced by commit
> :::::: 07d777fe8c3985bc83428c2866713c2d1b3d4129 tracing: Add percpu buffers for trace_printk()
>
> :::::: TO: Steven Rostedt <srostedt@redhat.com>
> :::::: CC: Steven Rostedt <rostedt@goodmis.org>
>
> ---
> 0-DAY kernel test infrastructure Open Source Technology Center
> https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org Intel Corporation
--
Thanks,
~Nick Desaulniers
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [trace:ftrace/core 29/38] kernel/trace/trace.c:3232:6: warning: variable 'buffer' is used uninitialized whenever 'if' condition is true
2020-01-22 22:02 ` [trace:ftrace/core 29/38] kernel/trace/trace.c:3232:6: warning: variable 'buffer' is used uninitialized whenever 'if' condition is true Nick Desaulniers
@ 2020-01-23 2:06 ` Steven Rostedt
0 siblings, 0 replies; 2+ messages in thread
From: Steven Rostedt @ 2020-01-23 2:06 UTC (permalink / raw)
To: kbuild-all
[-- Attachment #1: Type: text/plain, Size: 305 bytes --]
On Wed, 22 Jan 2020 14:02:56 -0800
Nick Desaulniers <ndesaulniers@google.com> wrote:
> +Steven, looks legit, can you please take a look?
Yes, I already fixed it and it's in my queue to be tested.
-- Steve
>
> On Wed, Jan 22, 2020 at 12:40 PM kbuild test robot <lkp@intel.com> wrote:
> >
>
^ permalink raw reply [flat|nested] 2+ messages in thread
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[not found] <202001230452.x1ZgvXCx%lkp@intel.com>
2020-01-22 22:02 ` [trace:ftrace/core 29/38] kernel/trace/trace.c:3232:6: warning: variable 'buffer' is used uninitialized whenever 'if' condition is true Nick Desaulniers
2020-01-23 2:06 ` Steven Rostedt
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