projects / thirdparty / kernel / stable-queue.git / blame
| Commit | Line | Data |
|---|---|---|
| 353de598 GKH |
1 | From af06d4f74a7d2132c805339bfd5ab771b5706f42 Mon Sep 17 00:00:00 2001 |
| 2 | From: Boqun Feng <boqun.feng@gmail.com> | |
| 3 | Date: Wed, 25 May 2016 09:25:33 +0800 | |
| 4 | Subject: rcuperf: Don't treat gp_exp mis-setting as a WARN | |
| 5 | ||
| 6 | From: Boqun Feng <boqun.feng@gmail.com> | |
| 7 | ||
| 8 | commit af06d4f74a7d2132c805339bfd5ab771b5706f42 upstream. | |
| 9 | ||
| 10 | 0day found a boot warning triggered in rcu_perf_writer() on !SMP kernel: | |
| 11 | ||
| 12 | WARN_ON(rcu_gp_is_normal() && gp_exp); | |
| 13 | ||
| 14 | , the root cause of which is trying to measure expedited grace | |
| 15 | periods(by setting gp_exp to true by default) when all the grace periods | |
| 16 | are normal(TINY RCU only has normal grace periods). | |
| 17 | ||
| 18 | However, such a mis-setting would only result in failing to measure the | |
| 19 | performance for a specific kind of grace periods, therefore using a | |
| 20 | WARN_ON to check this is a little overkilling. We could handle this | |
| 21 | inside rcuperf module via some error messages to tell users about the | |
| 22 | mis-settings. | |
| 23 | ||
| 24 | Therefore this patch removes the WARN_ON in rcu_perf_writer() and | |
| 25 | handles those checkings in rcu_perf_init() with plain if() code. | |
| 26 | ||
| 27 | Moreover, this patch changes the default value of gp_exp to 1) align | |
| 28 | with rcutorture tests and 2) make the default setting work for all RCU | |
| 29 | implementations by default. | |
| 30 | ||
| 31 | Suggested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> | |
| 32 | Signed-off-by: Boqun Feng <boqun.feng@gmail.com> | |
| 33 | Fixes: http://lkml.kernel.org/r/57411b10.mFvG0+AgcrMXGtcj%fengguang.wu@intel.com | |
| 34 | Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> | |
| 35 | Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> | |
| 36 | ||
| 37 | --- | |
| 38 | kernel/rcu/rcuperf.c | 14 +++++++++++--- | |
| 39 | 1 file changed, 11 insertions(+), 3 deletions(-) | |
| 40 | ||
| 41 | --- a/kernel/rcu/rcuperf.c | |
| 42 | +++ b/kernel/rcu/rcuperf.c | |
| 43 | @@ -58,7 +58,7 @@ MODULE_AUTHOR("Paul E. McKenney <paulmck | |
| 44 | #define VERBOSE_PERFOUT_ERRSTRING(s) \ | |
| 45 | do { if (verbose) pr_alert("%s" PERF_FLAG "!!! %s\n", perf_type, s); } while (0) | |
| 46 | ||
| 47 | -torture_param(bool, gp_exp, true, "Use expedited GP wait primitives"); | |
| 48 | +torture_param(bool, gp_exp, false, "Use expedited GP wait primitives"); | |
| 49 | torture_param(int, holdoff, 10, "Holdoff time before test start (s)"); | |
| 50 | torture_param(int, nreaders, -1, "Number of RCU reader threads"); | |
| 51 | torture_param(int, nwriters, -1, "Number of RCU updater threads"); | |
| 52 | @@ -363,8 +363,6 @@ rcu_perf_writer(void *arg) | |
| 53 | u64 *wdpp = writer_durations[me]; | |
| 54 | ||
| 55 | VERBOSE_PERFOUT_STRING("rcu_perf_writer task started"); | |
| 56 | - WARN_ON(rcu_gp_is_expedited() && !rcu_gp_is_normal() && !gp_exp); | |
| 57 | - WARN_ON(rcu_gp_is_normal() && gp_exp); | |
| 58 | WARN_ON(!wdpp); | |
| 59 | set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids)); | |
| 60 | sp.sched_priority = 1; | |
| 61 | @@ -631,6 +629,16 @@ rcu_perf_init(void) | |
| 62 | firsterr = -ENOMEM; | |
| 63 | goto unwind; | |
| 64 | } | |
| 65 | + if (rcu_gp_is_expedited() && !rcu_gp_is_normal() && !gp_exp) { | |
| 66 | + VERBOSE_PERFOUT_ERRSTRING("All grace periods expedited, no normal ones to measure!"); | |
| 67 | + firsterr = -EINVAL; | |
| 68 | + goto unwind; | |
| 69 | + } | |
| 70 | + if (rcu_gp_is_normal() && gp_exp) { | |
| 71 | + VERBOSE_PERFOUT_ERRSTRING("All grace periods normal, no expedited ones to measure!"); | |
| 72 | + firsterr = -EINVAL; | |
| 73 | + goto unwind; | |
| 74 | + } | |
| 75 | for (i = 0; i < nrealwriters; i++) { | |
| 76 | writer_durations[i] = | |
| 77 | kcalloc(MAX_MEAS, sizeof(*writer_durations[i]), |