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([2600:1004:b051:ad4e:accd:3cda:58d9:2348]) by smtp.gmail.com with ESMTPSA id c85sm3746327ywb.81.2020.03.01.12.53.10 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 01 Mar 2020 12:53:10 -0800 (PST) Date: Sun, 01 Mar 2020 15:53:07 -0500 User-Agent: K-9 Mail for Android In-Reply-To: References: <20200228174630.8989-1-madhuparnabhowmik10@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Subject: Re: [PATCH 1/2] drivers: base: power: main: Use built-in RCU list checking To: "Rafael J. Wysocki" , madhuparnabhowmik10@gmail.com CC: "Rafael J. Wysocki" , Pavel Machek , Len Brown , Greg Kroah-Hartman , Linux PM , Linux Kernel Mailing List , frextrite@gmail.com, linux-kernel-mentees@lists.linuxfoundation.org, paulmck@kernel.org From: joel@joelfernandes.org Message-ID: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On March 1, 2020 3:12:53 PM EST, "Rafael J=2E Wysocki" wrote: >On Fri, Feb 28, 2020 at 6:47 PM wrote: >> >> From: Madhuparna Bhowmik >> >> This patch passes the cond argument to list_for_each_entry_rcu() >> to fix the following false-positive lockdep warnings: >> >> [ 330=2E302784] =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D >> [ 330=2E302789] WARNING: suspicious RCU usage >> [ 330=2E302796] 5=2E6=2E0-rc1+ #5 Not tainted >> [ 330=2E302801] ----------------------------- >> [ 330=2E302808] drivers/base/power/main=2Ec:326 RCU-list traversed in >non-reader section!! >> >> [ 330=2E303303] =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D >> [ 330=2E303307] WARNING: suspicious RCU usage >> [ 330=2E303311] 5=2E6=2E0-rc1+ #5 Not tainted >> [ 330=2E303315] ----------------------------- >> [ 330=2E303319] drivers/base/power/main=2Ec:1698 RCU-list traversed in >non-reader section!! >> >> [ 331=2E934969] =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D >> [ 331=2E934971] WARNING: suspicious RCU usage >> [ 331=2E934973] 5=2E6=2E0-rc1+ #5 Not tainted >> [ 331=2E934975] ----------------------------- >> [ 331=2E934977] drivers/base/power/main=2Ec:1238 RCU-list traversed in >non-reader section!! >> >> [ 332=2E467772] WARNING: suspicious RCU usage >> [ 332=2E467775] 5=2E6=2E0-rc1+ #5 Not tainted >> [ 332=2E467775] ----------------------------- >> [ 332=2E467778] drivers/base/power/main=2Ec:269 RCU-list traversed in >non-reader section!! > >I don't see these warnings in the kernels run locally here=2E > >What do you do to get them? > >Joel, any comments here? You have to enable lockdep in your config=2E Does your setup have that? Thanks, - Joel > >> >> Signed-off-by: Madhuparna Bhowmik >> --- >> drivers/base/power/main=2Ec | 12 ++++++++---- >> 1 file changed, 8 insertions(+), 4 deletions(-) >> >> diff --git a/drivers/base/power/main=2Ec b/drivers/base/power/main=2Ec >> index 0e99a760aebd=2E=2E742c05f3c1e7 100644 >> --- a/drivers/base/power/main=2Ec >> +++ b/drivers/base/power/main=2Ec >> @@ -266,7 +266,8 @@ static void dpm_wait_for_suppliers(struct device >*dev, bool async) >> * callbacks freeing the link objects for the links in the >list we're >> * walking=2E >> */ >> - list_for_each_entry_rcu(link, &dev->links=2Esuppliers, c_node) >> + list_for_each_entry_rcu(link, &dev->links=2Esuppliers, c_node, >> + device_links_read_lock_held()) >> if (READ_ONCE(link->status) !=3D DL_STATE_DORMANT) >> dpm_wait(link->supplier, async); >> >> @@ -323,7 +324,8 @@ static void dpm_wait_for_consumers(struct device >*dev, bool async) >> * continue instead of trying to continue in parallel with >its >> * unregistration)=2E >> */ >> - list_for_each_entry_rcu(link, &dev->links=2Econsumers, s_node) >> + list_for_each_entry_rcu(link, &dev->links=2Econsumers, s_node, >> + device_links_read_lock_held()) >> if (READ_ONCE(link->status) !=3D DL_STATE_DORMANT) >> dpm_wait(link->consumer, async); >> >> @@ -1235,7 +1237,8 @@ static void dpm_superior_set_must_resume(struct >device *dev) >> >> idx =3D device_links_read_lock(); >> >> - list_for_each_entry_rcu(link, &dev->links=2Esuppliers, c_node) >> + list_for_each_entry_rcu(link, &dev->links=2Esuppliers, c_node, >> + device_links_read_lock_held()) >> link->supplier->power=2Emust_resume =3D true; >> >> device_links_read_unlock(idx); >> @@ -1695,7 +1698,8 @@ static void >dpm_clear_superiors_direct_complete(struct device *dev) >> >> idx =3D device_links_read_lock(); >> >> - list_for_each_entry_rcu(link, &dev->links=2Esuppliers, c_node) >{ >> + list_for_each_entry_rcu(link, &dev->links=2Esuppliers, c_node, >> + device_links_read_lock_held()) { >> spin_lock_irq(&link->supplier->power=2Elock); >> link->supplier->power=2Edirect_complete =3D false; >> spin_unlock_irq(&link->supplier->power=2Elock); >> -- >> 2=2E17=2E1 >> --=20 Sent from my Android device with K-9 Mail=2E Please excuse my brevity=2E