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Thu, 27 Oct 2022 14:12:21 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id xLxyAcWRWmPRBwAAMHmgww (envelope-from ); Thu, 27 Oct 2022 14:12:21 +0000 Date: Thu, 27 Oct 2022 16:12:19 +0200 From: Jean Delvare To: Chen Zhongjin Cc: , , Subject: Re: [PATCH v2] i2c: piix4: Fix adapter not be removed in piix4_remove() Message-ID: <20221027161219.1840104a@endymion.delvare> In-Reply-To: <20221027121353.181695-1-chenzhongjin@huawei.com> References: <20221027121353.181695-1-chenzhongjin@huawei.com> Organization: SUSE Linux X-Mailer: Claws Mail 3.18.0 (GTK+ 2.24.32; x86_64-suse-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-i2c@vger.kernel.org On Thu, 27 Oct 2022 20:13:53 +0800, Chen Zhongjin wrote: > In piix4_probe(), the piix4 adapter will be registered in: > > piix4_probe() > piix4_add_adapters_sb800() / piix4_add_adapter() > i2c_add_adapter() > > Based on the probed device type, piix4_add_adapters_sb800() or single > piix4_add_adapter() will be called. > For the former case, piix4_adapter_count is set as the number of adapters, > while for antoher case it is not set and kept default *zero*. > > When piix4 is removed, piix4_remove() removes the adapters added in > piix4_probe(), basing on the piix4_adapter_count value. > Because the count is zero for the single adapter case, the adapter won't > be removed and makes the sources allocated for adapter leaked, such as > the i2c client and device. > > These sources can still be accessed by i2c or bus and cause problems. > An easily reproduced case is that if a new adapter is registered, i2c > will get the leaked adapter and try to call smbus_algorithm, which was > already freed: > > Triggered by: rmmod i2c_piix4 && modprobe max31730 > > BUG: unable to handle page fault for address: ffffffffc053d860 > #PF: supervisor read access in kernel mode > #PF: error_code(0x0000) - not-present page > Oops: 0000 [#1] PREEMPT SMP KASAN > CPU: 0 PID: 3752 Comm: modprobe Tainted: G > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996) > RIP: 0010:i2c_default_probe (drivers/i2c/i2c-core-base.c:2259) i2c_core > RSP: 0018:ffff888107477710 EFLAGS: 00000246 > ... > > i2c_detect (drivers/i2c/i2c-core-base.c:2302) i2c_core > __process_new_driver (drivers/i2c/i2c-core-base.c:1336) i2c_core > bus_for_each_dev (drivers/base/bus.c:301) > i2c_for_each_dev (drivers/i2c/i2c-core-base.c:1823) i2c_core > i2c_register_driver (drivers/i2c/i2c-core-base.c:1861) i2c_core > do_one_initcall (init/main.c:1296) > do_init_module (kernel/module/main.c:2455) > ... > > ---[ end trace 0000000000000000 ]--- > > Fix this problem by correctly set piix4_adapter_count as 1 for the > single adapter so it can be normally removed. > > Fixes: 528d53a1592b ("i2c: piix4: Fix probing of reserved ports on AMD Family 16h Model 30h") > Signed-off-by: Chen Zhongjin > --- > v1 -> v2: > Set piix4_adapter_count as 1 rather than increase it and slightly fix > the commit message. > --- > drivers/i2c/busses/i2c-piix4.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/drivers/i2c/busses/i2c-piix4.c b/drivers/i2c/busses/i2c-piix4.c > index 39cb1b7bb865..809fbd014cd6 100644 > --- a/drivers/i2c/busses/i2c-piix4.c > +++ b/drivers/i2c/busses/i2c-piix4.c > @@ -1080,6 +1080,7 @@ static int piix4_probe(struct pci_dev *dev, const struct pci_device_id *id) > "", &piix4_main_adapters[0]); > if (retval < 0) > return retval; > + piix4_adapter_count = 1; > } > > /* Check for auxiliary SMBus on some AMD chipsets */ Reviewed-by: Jean Delvare I believe this qualifies for stable trees, so: Cc: stable@vger.kernel.org Thanks, -- Jean Delvare SUSE L3 Support