From patchwork Mon May 2 14:22:11 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Paul E. 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Violators will be prosecuted; Mon, 2 May 2016 08:38:51 -0600 X-IBM-Helo: d03dlp03.boulder.ibm.com X-IBM-MailFrom: paulmck@linux.vnet.ibm.com X-IBM-RcptTo: linux-kernel@vger.kernel.org;linux-omap@vger.kernel.org Received: from b01cxnp22035.gho.pok.ibm.com (b01cxnp22035.gho.pok.ibm.com [9.57.198.25]) by d03dlp03.boulder.ibm.com (Postfix) with ESMTP id 7EE4019D8059; Mon, 2 May 2016 08:38:34 -0600 (MDT) Received: from d01av01.pok.ibm.com (d01av01.pok.ibm.com [9.56.224.215]) by b01cxnp22035.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id u42Ecn1a26017824; Mon, 2 May 2016 14:38:49 GMT Received: from d01av01.pok.ibm.com (localhost [127.0.0.1]) by d01av01.pok.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id u42EclJZ026125; Mon, 2 May 2016 10:38:49 -0400 Received: from paulmck-ThinkPad-W541 ([9.70.82.191]) by d01av01.pok.ibm.com (8.14.4/8.14.4/NCO v10.0 AVin) with ESMTP id u42EckP8026069; Mon, 2 May 2016 10:38:47 -0400 Received: by paulmck-ThinkPad-W541 (Postfix, from userid 1000) id C6E5916C2A04; Mon, 2 May 2016 07:22:18 -0700 (PDT) From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org Cc: tony@atomide.com, mingo@kernel.org, linux@arm.linux.org.uk, rostedt@goodmis.org, linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org, "Paul E. McKenney" Subject: [PATCH omap 1/6] arm: Use _rcuidle tracepoint to allow use from idle Date: Mon, 2 May 2016 07:22:11 -0700 Message-Id: <1462198936-3496-1-git-send-email-paulmck@linux.vnet.ibm.com> X-Mailer: git-send-email 2.5.2 In-Reply-To: <20160502142117.GA2911@linux.vnet.ibm.com> References: <20160502142117.GA2911@linux.vnet.ibm.com> X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16050214-0013-0000-0000-0000353B5DF5 Sender: linux-omap-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-omap@vger.kernel.org X-Spam-Status: No, score=-7.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Testing on ARM encountered the following pair of lockdep-RCU splats: ------------------------------------------------------------------------ =============================== [ INFO: suspicious RCU usage. ] 4.6.0-rc4-next-20160422 #1 Not tainted ------------------------------- include/trace/events/power.h:328 suspicious rcu_dereference_check() usage! other info that might help us debug this: RCU used illegally from idle CPU! rcu_scheduler_active = 1, debug_locks = 0 RCU used illegally from extended quiescent state! no locks held by swapper/0/0. stack backtrace: CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.6.0-rc4-next-20160422 #1 Hardware name: Generic OMAP3-GP (Flattened Device Tree) [] (unwind_backtrace) from [] (show_stack+0x10/0x14) [] (show_stack) from [] (dump_stack+0xa8/0xe0) [] (dump_stack) from [] (pwrdm_set_next_pwrst+0xf8/0x1cc) [] (pwrdm_set_next_pwrst) from [] (omap3_enter_idle_bm+0x1b8/0x1e8) [] (omap3_enter_idle_bm) from [] (cpuidle_enter_state+0x84/0x408) [] (cpuidle_enter_state) from [] (cpu_startup_entry+0x1c8/0x3f0) [] (cpu_startup_entry) from [] (start_kernel+0x354/0x3cc) ------------------------------------------------------------------------ [] (unwind_backtrace) from [] (show_stack+0x10/0x14) [] (show_stack) from [] (dump_stack+0xa8/0xe0) [] (dump_stack) from [] (_pwrdm_state_switch+0x188/0x32c) [] (_pwrdm_state_switch) from [] (_pwrdm_post_transition_cb+0xc/0x14) [] (_pwrdm_post_transition_cb) from [] (pwrdm_for_each+0x30/0x5c) [] (pwrdm_for_each) from [] (pwrdm_post_transition+0x24/0x30) [] (pwrdm_post_transition) from [] (omap_sram_idle+0xfc/0x240) [] (omap_sram_idle) from [] (omap3_enter_idle_bm+0xf0/0x1e8) [] (omap3_enter_idle_bm) from [] (cpuidle_enter_state+0x84/0x408) [] (cpuidle_enter_state) from [] (cpu_startup_entry+0x1c8/0x3f0) [] (cpu_startup_entry) from [] (start_kernel+0x354/0x3cc) ------------------------------------------------------------------------ These are caused by event tracing from the idle loop, and they were exposed by commit 293e2421fe25 ("rcu: Remove superfluous versions of rcu_read_lock_sched_held()"), which suppressed some false negatives. The current commit therefore adds the _rcuidle suffix to make RCU aware of this implicit use of RCU by event tracing, thus preventing both splats. Reported-by: Guenter Roeck Signed-off-by: Paul E. McKenney Tested-by: Guenter Roeck Tested-by: Tony Lindgren Cc: Russell King Reviewed-by: Steven Rostedt Cc: Cc: --- arch/arm/mach-omap2/powerdomain.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/arch/arm/mach-omap2/powerdomain.c b/arch/arm/mach-omap2/powerdomain.c index 78af6d8cf2e2..daf2753de7aa 100644 --- a/arch/arm/mach-omap2/powerdomain.c +++ b/arch/arm/mach-omap2/powerdomain.c @@ -186,8 +186,9 @@ static int _pwrdm_state_switch(struct powerdomain *pwrdm, int flag) trace_state = (PWRDM_TRACE_STATES_FLAG | ((next & OMAP_POWERSTATE_MASK) << 8) | ((prev & OMAP_POWERSTATE_MASK) << 0)); - trace_power_domain_target(pwrdm->name, trace_state, - smp_processor_id()); + trace_power_domain_target_rcuidle(pwrdm->name, + trace_state, + smp_processor_id()); } break; default: @@ -523,8 +524,8 @@ int pwrdm_set_next_pwrst(struct powerdomain *pwrdm, u8 pwrst) if (arch_pwrdm && arch_pwrdm->pwrdm_set_next_pwrst) { /* Trace the pwrdm desired target state */ - trace_power_domain_target(pwrdm->name, pwrst, - smp_processor_id()); + trace_power_domain_target_rcuidle(pwrdm->name, pwrst, + smp_processor_id()); /* Program the pwrdm desired target state */ ret = arch_pwrdm->pwrdm_set_next_pwrst(pwrdm, pwrst); }