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| author | Heiko Carstens <heiko.carstens@de.ibm.com> | 2019-10-29 16:09:47 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-12-31 14:37:17 +0300 |
| commit | de3c88b857384e393979dc9b6e85bce88e010f64 (patch) | |
| tree | c2cba3e7764d50936791e32af880bcaee5180955 /arch/s390 | |
| parent | 17972ec7d6fff2d32e0a7022164402c25e264e2a (diff) | |
| download | linux-de3c88b857384e393979dc9b6e85bce88e010f64.tar.xz | |
s390/time: ensure get_clock_monotonic() returns monotonic values
[ Upstream commit 011620688a71f2f1fe9901dbc2479a7c01053196 ]
The current implementation of get_clock_monotonic() leaves it up to
the caller to call the function with preemption disabled. The only
core kernel caller (sched_clock) however does not disable preemption.
In order to make sure that all callers of this function see monotonic
values handle disabling preemption within the function itself.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'arch/s390')
| -rw-r--r-- | arch/s390/include/asm/timex.h | 16 |
1 files changed, 10 insertions, 6 deletions
diff --git a/arch/s390/include/asm/timex.h b/arch/s390/include/asm/timex.h index 64539c221672..0f12a3f91282 100644 --- a/arch/s390/include/asm/timex.h +++ b/arch/s390/include/asm/timex.h @@ -10,8 +10,9 @@ #ifndef _ASM_S390_TIMEX_H #define _ASM_S390_TIMEX_H -#include <asm/lowcore.h> +#include <linux/preempt.h> #include <linux/time64.h> +#include <asm/lowcore.h> /* The value of the TOD clock for 1.1.1970. */ #define TOD_UNIX_EPOCH 0x7d91048bca000000ULL @@ -186,15 +187,18 @@ extern unsigned char tod_clock_base[16] __aligned(8); /** * get_clock_monotonic - returns current time in clock rate units * - * The caller must ensure that preemption is disabled. * The clock and tod_clock_base get changed via stop_machine. - * Therefore preemption must be disabled when calling this - * function, otherwise the returned value is not guaranteed to - * be monotonic. + * Therefore preemption must be disabled, otherwise the returned + * value is not guaranteed to be monotonic. */ static inline unsigned long long get_tod_clock_monotonic(void) { - return get_tod_clock() - *(unsigned long long *) &tod_clock_base[1]; + unsigned long long tod; + + preempt_disable(); + tod = get_tod_clock() - *(unsigned long long *) &tod_clock_base[1]; + preempt_enable(); + return tod; } /** |