Commit 039958a5 authored Jan 24, 2020 by Vasily Averin Committed by Steven Rostedt (VMware) Jan 30, 2020

tracing: eval_map_next() should always increase position index

if seq_file .next fuction does not change position index,
read after some lseek can generate unexpected output.

Link: http://lkml.kernel.org/r/7ad85b22-1866-977c-db17-88ac438bc764@virtuozzo.com



Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
[ This is not a bug fix, it just makes it "technically correct"
  which is why I applied it. NULL is only returned on an anomaly
  which triggers a WARN_ON ]
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

parent e4075e8b

kernel/trace/trace.c

+1 −3

Original line number	Diff line number	Diff line
		@@ -5399,14 +5399,12 @@ static void eval_map_next(struct seq_file m, void v, loff_t pos)
		* Paranoid! If ptr points to end, we don't want to increment past it.
		* This really should never happen.
		*/
		(*pos)++;
		ptr = update_eval_map(ptr);
		if (WARN_ON_ONCE(!ptr))
		return NULL;

		ptr++;

		(*pos)++;

		ptr = update_eval_map(ptr);

		return ptr;

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