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| author | Paul E. McKenney <paulmck@kernel.org> | 2022-02-28 18:08:33 -0800 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2022-04-20 16:50:30 -0700 |
| commit | 3791a22374715b36ad806db13d8b2afb1b57fd36 (patch) | |
| tree | 25b19ea4929a89ab2776f6f2f1b20de3b2863886 /kernel/smp.c | |
| parent | c708b08c65a0dfae127b9ee33b0fb73535a5e066 (diff) | |
| download | lwn-3791a22374715b36ad806db13d8b2afb1b57fd36.tar.gz lwn-3791a22374715b36ad806db13d8b2afb1b57fd36.zip | |
kernel/smp: Provide boot-time timeout for CSD lock diagnostics
Debugging of problems involving insanely long-running SMI handlers
proceeds better if the CSD-lock timeout can be adjusted. This commit
therefore provides a new smp.csd_lock_timeout kernel boot parameter
that specifies the timeout in milliseconds. The default remains at the
previously hard-coded value of five seconds.
[ paulmck: Apply feedback from Juergen Gross. ]
Cc: Rik van Riel <riel@surriel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'kernel/smp.c')
| -rw-r--r-- | kernel/smp.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/kernel/smp.c b/kernel/smp.c index 01a7c1706a58..6a1f1daa3dc4 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -183,7 +183,9 @@ static DEFINE_PER_CPU(smp_call_func_t, cur_csd_func); static DEFINE_PER_CPU(void *, cur_csd_info); static DEFINE_PER_CPU(struct cfd_seq_local, cfd_seq_local); -#define CSD_LOCK_TIMEOUT (5ULL * NSEC_PER_SEC) +static ulong csd_lock_timeout = 5000; /* CSD lock timeout in milliseconds. */ +module_param(csd_lock_timeout, ulong, 0444); + static atomic_t csd_bug_count = ATOMIC_INIT(0); static u64 cfd_seq; @@ -329,6 +331,7 @@ static bool csd_lock_wait_toolong(struct __call_single_data *csd, u64 ts0, u64 * u64 ts2, ts_delta; call_single_data_t *cpu_cur_csd; unsigned int flags = READ_ONCE(csd->node.u_flags); + unsigned long long csd_lock_timeout_ns = csd_lock_timeout * NSEC_PER_MSEC; if (!(flags & CSD_FLAG_LOCK)) { if (!unlikely(*bug_id)) @@ -341,7 +344,7 @@ static bool csd_lock_wait_toolong(struct __call_single_data *csd, u64 ts0, u64 * ts2 = sched_clock(); ts_delta = ts2 - *ts1; - if (likely(ts_delta <= CSD_LOCK_TIMEOUT)) + if (likely(ts_delta <= csd_lock_timeout_ns || csd_lock_timeout_ns == 0)) return false; firsttime = !*bug_id; |