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Wysocki" Cc: Samuel Holland , Albert Ou , Anup Patel , Atish Patra , Geert Uytterhoeven , Heiko Stuebner , Kai-Heng Feng , Luis Chamberlain , "Paul E. McKenney" , Paul Walmsley , Petr Mladek , YueHaibing , linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, tangmeng Subject: [PATCH 1/3] kernel/reboot: Use the static sys-off handler for any priority Date: Wed, 28 Dec 2022 10:19:13 -0600 Message-Id: <20221228161915.13194-2-samuel@sholland.org> X-Mailer: git-send-email 2.37.4 In-Reply-To: <20221228161915.13194-1-samuel@sholland.org> References: <20221228161915.13194-1-samuel@sholland.org> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" commit 587b9bfe0668 ("kernel/reboot: Use static handler for register_platform_power_off()") addded a statically-allocated handler so register_sys_off_handler() could be called before the slab allocator is available. That behavior was limited to the SYS_OFF_PRIO_PLATFORM priority. However, it is also required for handlers such as PSCI on ARM and SBI on RISC-V, which should be registered at SYS_OFF_PRIO_FIRMWARE. Currently, this call stack crashes: start_kernel() setup_arch() psci_dt_init() psci_0_2_init() register_sys_off_handler() kmem_cache_alloc() Generalize the code to use the statically-allocated handler for the first registration, regardless of priority. Check .sys_off_cb for conflicts instead of .cb_data; some callbacks (e.g. firmware drivers) do not need any per-instance data, so .cb_data could be NULL. Reviewed-by: Dmitry Osipenko Signed-off-by: Samuel Holland --- kernel/reboot.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) diff --git a/kernel/reboot.c b/kernel/reboot.c index 3bba88c7ffc6..38c18d4f0a36 100644 --- a/kernel/reboot.c +++ b/kernel/reboot.c @@ -327,7 +327,7 @@ static int sys_off_notify(struct notifier_block *nb, return handler->sys_off_cb(&data); } =20 -static struct sys_off_handler platform_sys_off_handler; +static struct sys_off_handler early_sys_off_handler; =20 static struct sys_off_handler *alloc_sys_off_handler(int priority) { @@ -338,10 +338,8 @@ static struct sys_off_handler *alloc_sys_off_handler(i= nt priority) * Platforms like m68k can't allocate sys_off handler dynamically * at the early boot time because memory allocator isn't available yet. */ - if (priority =3D=3D SYS_OFF_PRIO_PLATFORM) { - handler =3D &platform_sys_off_handler; - if (handler->cb_data) - return ERR_PTR(-EBUSY); + if (!early_sys_off_handler.sys_off_cb) { + handler =3D &early_sys_off_handler; } else { if (system_state > SYSTEM_RUNNING) flags =3D GFP_ATOMIC; @@ -358,7 +356,7 @@ static struct sys_off_handler *alloc_sys_off_handler(in= t priority) =20 static void free_sys_off_handler(struct sys_off_handler *handler) { - if (handler =3D=3D &platform_sys_off_handler) + if (handler =3D=3D &early_sys_off_handler) memset(handler, 0, sizeof(*handler)); else kfree(handler); --=20 2.37.4