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Wysocki" To: Linux PM Cc: LKML , Ulf Hansson , Stanislaw Gruszka Subject: [PATCH v1 01/12] PM: sleep: Simplify dpm_suspended_list walk in dpm_resume() Date: Mon, 22 Jan 2024 12:22:38 +0100 Message-ID: <4553341.LvFx2qVVIh@kreacher> In-Reply-To: <5760158.DvuYhMxLoT@kreacher> References: <5760158.DvuYhMxLoT@kreacher> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CLIENT-IP: 195.136.19.94 X-CLIENT-HOSTNAME: 195.136.19.94 X-VADE-SPAMSTATE: clean X-VADE-SPAMCAUSE: gggruggvucftvghtrhhoucdtuddrgedvkedrvdekiedgfedtucetufdoteggodetrfdotffvucfrrhhofhhilhgvmecujffqoffgrffnpdggtffipffknecuuegrihhlohhuthemucduhedtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmdenucfjughrpefhvfevufffkfgjfhgggfgtsehtufertddttdejnecuhfhrohhmpedftfgrfhgrvghlucflrdcuhgihshhotghkihdfuceorhhjfiesrhhjfiihshhotghkihdrnhgvtheqnecuggftrfgrthhtvghrnhepvdffueeitdfgvddtudegueejtdffteetgeefkeffvdeftddttdeuhfegfedvjefhnecukfhppeduleehrddufeeirdduledrleegnecuvehluhhsthgvrhfuihiivgepfeenucfrrghrrghmpehinhgvthepudelhedrudefiedrudelrdelgedphhgvlhhopehkrhgvrggthhgvrhdrlhhotggrlhhnvghtpdhmrghilhhfrhhomhepfdftrghfrggvlhculfdrucghhihsohgtkhhifdcuoehrjhifsehrjhifhihsohgtkhhirdhnvghtqedpnhgspghrtghpthhtohepgedprhgtphhtthhopehlihhnuhigqdhpmhesvhhgvghrrdhkvghrnhgvlhdrohhrghdprhgtphhtthhopehlihhnuhigqdhkvghrnhgvlhesvhhgvghrrdhkvghrnhgvlhdrohhrghdprhgtphhtthhopehulhhfrdhhrghnshhsohhnsehlihhnrghrohdrohhrghdprhgtphhtthhopehsthgrnhhishhlrgifrdhgrhhushiikhgrsehlihhnuhigrdhinhhtvghlrdgtohhm X-DCC--Metrics: v370.home.net.pl 1024; Body=4 Fuz1=4 Fuz2=4 Content-Type: text/plain; charset="utf-8" From: Rafael J. Wysocki Notice that devices can be moved to dpm_prepared_list before running their resume callbacks, in analogy with dpm_noirq_resume_devices() and dpm_resume_early(), because doing so will not affect the final ordering of that list. Namely, if a device is the first dpm_suspended_list entry while dpm_list_mtx is held, it has not been removed so far and it cannot be removed until dpm_list_mtx is released, so moving it to dpm_prepared_list at that point is valid. If it is removed later, while its resume callback is running, it will be deleted from dpm_prepared_list without changing the ordering of the other devices in that list. Accordingly, rearrange the while () loop in dpm_resume() to move devices to dpm_prepared_list before running their resume callbacks and implify the locking and device reference counting in it. No intentional functional impact. Signed-off-by: Rafael J. Wysocki Reviewed-by: Stanislaw Gruszka --- drivers/base/power/main.c | 16 +++++----------- 1 file changed, 5 insertions(+), 11 deletions(-) Index: linux-pm/drivers/base/power/main.c =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=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=3D=3D=3D=3D=3D=3D=3D=3D=3D --- linux-pm.orig/drivers/base/power/main.c +++ linux-pm/drivers/base/power/main.c @@ -1017,25 +1017,19 @@ void dpm_resume(pm_message_t state) =20 while (!list_empty(&dpm_suspended_list)) { dev =3D to_device(dpm_suspended_list.next); - - get_device(dev); + list_move_tail(&dev->power.entry, &dpm_prepared_list); =20 if (!dev->power.async_in_progress) { + get_device(dev); + mutex_unlock(&dpm_list_mtx); =20 device_resume(dev, state, false); =20 + put_device(dev); + mutex_lock(&dpm_list_mtx); } - - if (!list_empty(&dev->power.entry)) - list_move_tail(&dev->power.entry, &dpm_prepared_list); - - mutex_unlock(&dpm_list_mtx); - - put_device(dev); - - mutex_lock(&dpm_list_mtx); } mutex_unlock(&dpm_list_mtx); async_synchronize_full();