Messages in this thread | | | Subject | Re: [PATCH tip v4 4/5] rcu: Do not call rcu_nocb_gp_cleanup() while holding rnp->lock | From | Daniel Wagner <> | Date | Wed, 25 Nov 2015 11:29:05 +0100 |
| |
Hi Boqun,
On 11/25/2015 02:01 AM, Boqun Feng wrote: > On Tue, Nov 24, 2015 at 11:52:12PM +0800, Boqun Feng wrote: >> Hi Daniel, >> >> On Tue, Nov 24, 2015 at 02:03:06PM +0100, Daniel Wagner wrote: >>> rcu_nocb_gp_cleanup() is called while holding rnp->lock. Currently, >>> this is okay because the wake_up_all() in rcu_nocb_gp_cleanup() will >>> not enable the IRQs. lockdep is happy. >>> >>> By switching over using swait this is not true anymore. swake_up_all() >>> enables the IRQs while processing the waiters. __do_softirq() can now >>> run and will eventually call rcu_process_callbacks() which wants to >>> grap nrp->lock. >>> >>> Let's move the rcu_nocb_gp_cleanup() call outside the lock before we >>> switch over to swait. >>> >> >> But you did introduce swait in this patch ;-)
Argh, that is a fail. I did build all patches individual but seems like I haven't got the right configuration.
>> [snip] >> >>> >>> Signed-off-by: Daniel Wagner <daniel.wagner@bmw-carit.de> >>> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> >>> Cc: Peter Zijlstra <peterz@infradead.org> >>> Cc: Thomas Gleixner <tglx@linutronix.de> >>> Cc: linux-kernel@vger.kernel.org >>> --- >>> kernel/rcu/tree.c | 4 +++- >>> kernel/rcu/tree.h | 3 ++- >>> kernel/rcu/tree_plugin.h | 16 +++++++++++++--- >>> 3 files changed, 18 insertions(+), 5 deletions(-) >>> >> >> So I tried to build this patch with a config having RCU_EXPERT=y and >> RCU_NOCB_CPU=y, but I got:
Will update my config accordingly.
Thanks, Daniel
| |