| Message ID | 3f15868475cb4b32353885ee03c983209279fa81.1517192387.git.baolin.wang@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] kdb: use ktime_get_mono_fast_ns() instead of ktime_get_ts() | expand |
On Mon, Jan 29, 2018 at 10:22:51AM +0800, Baolin Wang wrote: > The kdb code will print the monotonic time by ktime_get_ts(), but > the ktime_get_ts() will be protected by a sequence lock, that will > introduce one deadlock risk if the lock was already held in the > context from which we entered the debugger. > > Thus we can use the ktime_get_mono_fast_ns() to get the monotonic > time, which is NMI safe access to clock monotonic. Moreover we can > remove the 'struct timespec', which is not y2038 safe. > > Signed-off-by: Baolin Wang <baolin.wang@linaro.org> Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org> > --- > Changes since v1: > - Use ktime_get_mono_fast_ns() instead of ktime_get_seconds(). > --- > kernel/debug/kdb/kdb_main.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c > index 69e70f4..bf1d0e0 100644 > --- a/kernel/debug/kdb/kdb_main.c > +++ b/kernel/debug/kdb/kdb_main.c > @@ -2486,10 +2486,10 @@ static int kdb_kill(int argc, const char **argv) > */ > static void kdb_sysinfo(struct sysinfo *val) > { > - struct timespec uptime; > - ktime_get_ts(&uptime); > + u64 uptime = ktime_get_mono_fast_ns(); > + > memset(val, 0, sizeof(*val)); > - val->uptime = uptime.tv_sec; > + val->uptime = div_u64(uptime, NSEC_PER_SEC); > val->loads[0] = avenrun[0]; > val->loads[1] = avenrun[1]; > val->loads[2] = avenrun[2]; > -- > 1.7.9.5 >
On Mon, Jan 29, 2018 at 3:22 AM, Baolin Wang <baolin.wang@linaro.org> wrote: > The kdb code will print the monotonic time by ktime_get_ts(), but > the ktime_get_ts() will be protected by a sequence lock, that will > introduce one deadlock risk if the lock was already held in the > context from which we entered the debugger. > > Thus we can use the ktime_get_mono_fast_ns() to get the monotonic > time, which is NMI safe access to clock monotonic. Moreover we can > remove the 'struct timespec', which is not y2038 safe. > > Signed-off-by: Baolin Wang <baolin.wang@linaro.org> Reviewed-by: Arnd Bergmann <arnd@arndb.de>
On 01/30/2018 07:35 AM, Arnd Bergmann wrote: > On Mon, Jan 29, 2018 at 3:22 AM, Baolin Wang <baolin.wang@linaro.org> wrote: >> The kdb code will print the monotonic time by ktime_get_ts(), but >> the ktime_get_ts() will be protected by a sequence lock, that will >> introduce one deadlock risk if the lock was already held in the >> context from which we entered the debugger. >> >> Thus we can use the ktime_get_mono_fast_ns() to get the monotonic >> time, which is NMI safe access to clock monotonic. Moreover we can >> remove the 'struct timespec', which is not y2038 safe. >> >> Signed-off-by: Baolin Wang <baolin.wang@linaro.org> > > Reviewed-by: Arnd Bergmann <arnd@arndb.de> > I'll add this in today, run some tests and it should be in the merge window. Thanks, Jason
diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c index 69e70f4..bf1d0e0 100644 --- a/kernel/debug/kdb/kdb_main.c +++ b/kernel/debug/kdb/kdb_main.c @@ -2486,10 +2486,10 @@ static int kdb_kill(int argc, const char **argv) */ static void kdb_sysinfo(struct sysinfo *val) { - struct timespec uptime; - ktime_get_ts(&uptime); + u64 uptime = ktime_get_mono_fast_ns(); + memset(val, 0, sizeof(*val)); - val->uptime = uptime.tv_sec; + val->uptime = div_u64(uptime, NSEC_PER_SEC); val->loads[0] = avenrun[0]; val->loads[1] = avenrun[1]; val->loads[2] = avenrun[2];
The kdb code will print the monotonic time by ktime_get_ts(), but the ktime_get_ts() will be protected by a sequence lock, that will introduce one deadlock risk if the lock was already held in the context from which we entered the debugger. Thus we can use the ktime_get_mono_fast_ns() to get the monotonic time, which is NMI safe access to clock monotonic. Moreover we can remove the 'struct timespec', which is not y2038 safe. Signed-off-by: Baolin Wang <baolin.wang@linaro.org> --- Changes since v1: - Use ktime_get_mono_fast_ns() instead of ktime_get_seconds(). --- kernel/debug/kdb/kdb_main.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) -- 1.7.9.5