Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
Merge tag 'csd-lock.2024.11.16a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu
Pull CSD-lock update from Paul McKenney:
"This switches from sched_clock() to ktime_get_mono_fast_ns(), which on
x86 switches from the rdtsc instruction to the rdtscp instruction,
thus avoiding instruction reorderings that cause false-positive
reports of CSD-lock stalls of almost 2^46 nanoseconds. These false
positives are rare, but really are seen in the wild"
* tag 'csd-lock.2024.11.16a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu:
locking/csd-lock: Switch from sched_clock() to ktime_get_mono_fast_ns()
+2
-2
+2
-2
kernel/smp.c
+2
-2
kernel/smp.c
···
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246
return true;
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}
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248
249
-
ts2 = sched_clock();
249
+
ts2 = ktime_get_mono_fast_ns();
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250
/* How long since we last checked for a stuck CSD lock.*/
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ts_delta = ts2 - *ts1;
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252
if (likely(ts_delta <= csd_lock_timeout_ns * (*nmessages + 1) *
···
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321
int bug_id = 0;
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u64 ts0, ts1;
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324
-
ts1 = ts0 = sched_clock();
324
+
ts1 = ts0 = ktime_get_mono_fast_ns();
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for (;;) {
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if (csd_lock_wait_toolong(csd, ts0, &ts1, &bug_id, &nmessages))
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break;