Messages in this thread | | | Date | Thu, 17 Aug 2023 20:24:32 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [paulmck-rcu:locktorture.2023.08.17a 14/20] kernel/rcu/tree.c:4100:6: warning: no previous declaration for 'rcu_barrier_throttled' |
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On Fri, Aug 18, 2023 at 09:02:35AM +0800, kernel test robot wrote: > tree: https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git locktorture.2023.08.17a > head: ccd7c62460a1ca6a8fb800de0d50d973ba62dcb8 > commit: 365332de5f7bd1ab448ad4a6bd73a4fc8f1cc8ec [14/20] rcu: Add sysfs to provide throttled access to rcu_barrier() > config: x86_64-randconfig-x071-20230818 (https://download.01.org/0day-ci/archive/20230818/202308180853.brWVZKoo-lkp@intel.com/config) > compiler: gcc-7 (Ubuntu 7.5.0-6ubuntu2) 7.5.0 > reproduce: (https://download.01.org/0day-ci/archive/20230818/202308180853.brWVZKoo-lkp@intel.com/reproduce) > > If you fix the issue in a separate patch/commit (i.e. not just a new version of > the same patch/commit), kindly add following tags > | Reported-by: kernel test robot <lkp@intel.com> > | Closes: https://lore.kernel.org/oe-kbuild-all/202308180853.brWVZKoo-lkp@intel.com/ > > All warnings (new ones prefixed by >>): > > >> kernel/rcu/tree.c:4100:6: warning: no previous declaration for 'rcu_barrier_throttled' [-Wmissing-declarations] > void rcu_barrier_throttled(void) > ^~~~~~~~~~~~~~~~~~~~~
This has since been declared static in a later version of this commit at:
f9d771b016ca ("rcu: Add sysfs to provide throttled access to rcu_barrier()")
Thank you for your testing efforts!
Thanx, Paul
> vim +/rcu_barrier_throttled +4100 kernel/rcu/tree.c > > 4083 > 4084 /** > 4085 * rcu_barrier_throttled - Do rcu_barrier(), but limit to one per second > 4086 * > 4087 * This can be thought of as guard rails around rcu_barrier() that > 4088 * permits unrestricted userspace use, at least assuming the hardware's > 4089 * try_cmpxchg() is robust. There will be at most one call per second to > 4090 * rcu_barrier() system-wide from use of this function, which means that > 4091 * callers might needlessly wait a second or three. > 4092 * > 4093 * This is intended for use by test suites to avoid OOM by flushing RCU > 4094 * callbacks from the previous test before starting the next. See the > 4095 * rcutree.do_rcu_barrier module parameter for more information. > 4096 * > 4097 * Why not simply make rcu_barrier() more scalable? That might be the > 4098 * eventual endpoint, but let's keep it simple for the time being. > 4099 */ > > 4100 void rcu_barrier_throttled(void) > 4101 { > 4102 unsigned long j = jiffies; > 4103 unsigned long old = READ_ONCE(rcu_barrier_last_throttle); > 4104 unsigned long s = rcu_seq_snap(&rcu_state.barrier_sequence); > 4105 > 4106 while (time_after(old + HZ, j) || !try_cmpxchg(&rcu_barrier_last_throttle, &old, j + HZ)) { > 4107 schedule_timeout_idle(HZ); > 4108 if (rcu_seq_done(&rcu_state.barrier_sequence, s)) > 4109 return; > 4110 old = READ_ONCE(rcu_barrier_last_throttle); > 4111 } > 4112 rcu_barrier(); > 4113 } > 4114 > > -- > 0-DAY CI Kernel Test Service > https://github.com/intel/lkp-tests/wiki
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