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time/timekeeping: Work around false positive GCC warning

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Newer GCC versions trigger the following warning:

  kernel/time/timekeeping.c: In function ‘get_device_system_crosststamp’:
  kernel/time/timekeeping.c:987:5: warning: ‘clock_was_set_seq’ may be used uninitialized in this function [-Wmaybe-uninitialized]
    if (discontinuity) {
     ^
  kernel/time/timekeeping.c:1045:15: note: ‘clock_was_set_seq’ was declared here
    unsigned int clock_was_set_seq;
                 ^

GCC clearly is unable to recognize that the 'do_interp' boolean tracks
the initialization status of 'clock_was_set_seq'.

The GCC version used was:

  gcc version 5.3.1 20151207 (Red Hat 5.3.1-2) (GCC)

Work it around by initializing clock_was_set_seq to 0. Compilers that
are able to recognize the code flow will eliminate the unnecessary
initialization.

Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Ingo Molnar
2016-03-08 11:09:53 +01:00
parent 6936527233
commit 6436257b49
1 changed files with 1 additions and 1 deletions
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2
kernel/time/timekeeping.c
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@@ -1042,7 +1042,7 @@ int get_device_system_crosststamp(int (*get_time_fn)
struct system_counterval_t system_counterval; struct system_counterval_t system_counterval;
struct timekeeper *tk = &tk_core.timekeeper; struct timekeeper *tk = &tk_core.timekeeper;
cycle_t cycles, now, interval_start; cycle_t cycles, now, interval_start;
unsigned int clock_was_set_seq; unsigned int clock_was_set_seq = 0;
ktime_t base_real, base_raw; ktime_t base_real, base_raw;
s64 nsec_real, nsec_raw; s64 nsec_real, nsec_raw;
u8 cs_was_changed_seq; u8 cs_was_changed_seq;