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Tue, 24 Nov 2020 12:03:23 +0000 (GMT) Subject: Re: [PATCH v2 2/3] spi: Use bus_type functions for probe, remove and shutdown To: =?UTF-8?Q?Uwe_Kleine-K=c3=b6nig?= , Mark Brown Cc: linux-spi@vger.kernel.org, linux-kernel@vger.kernel.org, kernel@pengutronix.de, Greg Kroah-Hartman , Bartlomiej Zolnierkiewicz From: Marek Szyprowski Message-ID: <9b86504f-c5f4-4c85-9bef-3d1ee4cbaf9c@samsung.com> Date: Tue, 24 Nov 2020 13:03:25 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.5.0 MIME-Version: 1.0 In-Reply-To: <20201119161604.2633521-2-u.kleine-koenig@pengutronix.de> Content-Transfer-Encoding: 8bit Content-Language: en-US X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFprHKsWRmVeSWpSXmKPExsWy7djP87o93/bEG6zbJ22xccZ6VoupD5+w WTQvXs9msWrqThaLy7vmsFk0frzJbnF74mRGB3aPTas62Tz2z13D7tH/18Cjb8sqRo/Pm+QC WKO4bFJSczLLUov07RK4Mg78+c5UsFmt4svTNSwNjPPluxg5OSQETCQuLW5g62Lk4hASWMEo cerPASjnC6PExyvvmSGcz4wSpxecZINp+XbgHjtEYjmjxMSnrSwgCSGB94wSHUucQGxhgQiJ vsPvWUFsEYFMiQmX3zGCNDAL7GWUODv7DjNIgk3AUKLrbRfYVF4BO4nLbZ/ZQWwWAVWJfd+W gdmiAkkSBz8+gKoRlDg58wnYMk4BN4mHGzoYQWxmAXmJ5q2zmSFscYlbT+YzgSyTELjBIbF4 7QKos10kdr3YxQRhC0u8Or6FHcKWkfi/E6ahmVHi4bm17BBOD6PE5aYZjBBV1hJ3zv0CmsQB tEJTYv0ufYiwo8Tk89NZQMISAnwSN94KQhzBJzFp23RmiDCvREebEES1msSs4+vg1h68cIl5 AqPSLCSvzULyziwk78xC2LuAkWUVo3hqaXFuemqxYV5quV5xYm5xaV66XnJ+7iZGYBI6/e/4 px2Mc1991DvEyMTBeIhRgoNZSYS3VW5nvBBvSmJlVWpRfnxRaU5q8SFGaQ4WJXHeVbPXxAsJ pCeWpGanphakFsFkmTg4pRqYSnlSur4277qR+H+etS2PtH/Ptvaja6+XX5bM4GmdsfZg9xKu xXf/OPo+N8yYK6sVlKpo551ZWpdweebS/E/cLPcsquMzGh6++zhPVf/Ut5UuEoGcXzMfc9ZP fhcouLUlW3bVNqXT+Ws33JB6eFwyYUPTf+3VBvprdnGZHtIU7p23c/+2N2X1q0wU9fdGSp1p sNb/8UWua821Y01/z5qcu2x6/ZNAiayt+64sRpkFFm+WVD/bmatndMfIPM9UQGWS9d0DrXeu iv1I/q0XqDSrbrZi8fpI6fjbNr094tpHu2+fVPxpWPHHJ7OHQ91bqdo/rSWm4Pu22TN2n5wp mHd82a1/c/mkvjSKHVgU5P1MiaU4I9FQi7moOBEA33YE4LEDAAA= X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFtrIIsWRmVeSWpSXmKPExsVy+t/xe7o93/bEG3RMZLHYOGM9q8XUh0/Y LJoXr2ezWDV1J4vF5V1z2CwaP95kt7g9cTKjA7vHplWdbB77565h9+j/a+DRt2UVo8fnTXIB rFF6NkX5pSWpChn5xSW2StGGFkZ6hpYWekYmlnqGxuaxVkamSvp2NimpOZllqUX6dgl6GQf+ fGcq2KxW8eXpGpYGxvnyXYycHBICJhLfDtxj72Lk4hASWMooserBGVaIhIzEyWkNULawxJ9r XWwQRW8ZJX6c3sgIkhAWiJA4vH4lG4gtIpApceP9WiaQImaBvYwSR14tYIboaGSU+LVhLlgH m4ChRNfbLrAOXgE7icttn9lBbBYBVYl935aB2aICSRK/l66FqhGUODnzCQuIzSngJvFwQwfY HGYBM4l5mx8yQ9jyEs1bZ0PZ4hK3nsxnmsAoNAtJ+ywkLbOQtMxC0rKAkWUVo0hqaXFuem6x kV5xYm5xaV66XnJ+7iZGYNxtO/Zzyw7Gla8+6h1iZOJgPMQowcGsJMLbKrczXog3JbGyKrUo P76oNCe1+BCjKdA/E5mlRJPzgZGfVxJvaGZgamhiZmlgamlmrCTOa3JkTbyQQHpiSWp2ampB ahFMHxMHp1QDE9f9Rw92qTk2x7kYqNzTCd2wcOdj1gcO3N9W5ywQT1J1vn9aeZ8I9yS7qyVT Fq5PvGb1KleQ89qyOJdMnsOtYXOqy+66eb3Z/0mJJ0l/W/DXaPdw9W0vIlcnHLvZldfUeSLg 2avU+4fmbPbNbEv4rr3si+NUrfDlCyw/MOeI7zu9/fP7/B380lvna71xuajlO/XQBds7QgIN hSufKR7aX7VCYinLuYiFFa4TV69/oMDxIsDaOTWotD/6bpR2rbpKq+dCvz3aOS8+bthlxvNU fmmgbkqwZCGXi+tuzzW+/Yfd3RIbH6yrUbzs8Sfz0b0AlxXy7d9e/56S9mRzzOJpFrXTgj5P mLiB85GvReipJCWW4oxEQy3mouJEALC+sahEAwAA X-CMS-MailID: 20201124120324eucas1p189ec6eed6d6477e27a194f9d75d7b43a X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" X-RootMTR: 20201124120324eucas1p189ec6eed6d6477e27a194f9d75d7b43a X-EPHeader: CA CMS-TYPE: 201P X-CMS-RootMailID: 20201124120324eucas1p189ec6eed6d6477e27a194f9d75d7b43a References: <20201119161604.2633521-1-u.kleine-koenig@pengutronix.de> <20201119161604.2633521-2-u.kleine-koenig@pengutronix.de> Precedence: bulk List-ID: X-Mailing-List: linux-spi@vger.kernel.org Hi Uwe, On 19.11.2020 17:16, Uwe Kleine-König wrote: > The eventual goal is to get rid of the callbacks in struct > device_driver. Other than not using driver callbacks there should be no > side effect of this patch. > > Signed-off-by: Uwe Kleine-König This patch landed recently in linux-next as commit 9db34ee64ce4 ("spi: Use bus_type functions for probe, remove and shutdown"). It causes a regression on some of my test boards: Unable to handle kernel NULL pointer dereference at virtual address 0000000000000018 Mem abort info:   ESR = 0x96000004   EC = 0x25: DABT (current EL), IL = 32 bits   SET = 0, FnV = 0   EA = 0, S1PTW = 0 Data abort info:   ISV = 0, ISS = 0x00000004   CM = 0, WnR = 0 user pgtable: 4k pages, 48-bit VAs, pgdp=00000000318ed000 [0000000000000018] pgd=0000000000000000, p4d=0000000000000000 Internal error: Oops: 96000004 [#1] PREEMPT SMP Modules linked in: cpufreq_powersave cpufreq_conservative brcmfmac brcmutil cfg80211 crct10dif_ce s3fwrn5_i2c s3fwrn5 nci nfc s5p_mfc s5p_jpeg hci_uart btqca btbc buf2_dma_contig videobuf2_memops videobuf2_v4l2 bluetooth videobuf2_common videodev panfrost gpu_sched ecdh_generic mc ecc rfkill ip_tables x_tables ipv6 CPU: 0 PID: 1 Comm: systemd-shutdow Not tainted 5.10.0-rc5-next-20201124+ #9771 Hardware name: Samsung TM2E board (DT) pstate: 60000005 (nZCv daif -PAN -UAO -TCO BTYPE=--) pc : spi_shutdown+0x10/0x38 lr : device_shutdown+0x10c/0x350 sp : ffff80001311bc70 ... Call trace:  spi_shutdown+0x10/0x38  kernel_restart_prepare+0x34/0x40  kernel_restart+0x14/0x88  __do_sys_reboot+0x148/0x248  __arm64_sys_reboot+0x1c/0x28  el0_svc_common.constprop.3+0x74/0x198  do_el0_svc+0x20/0x98  el0_sync_handler+0x140/0x1a8  el0_sync+0x140/0x180 Code: f9403402 d1008041 f100005f 9a9f1021 (f9400c21) ---[ end trace 266c07205a2d632e ]--- Kernel panic - not syncing: Oops: Fatal exception Kernel Offset: disabled CPU features: 0x0240022,65006087 Memory Limit: none ---[ end Kernel panic - not syncing: Oops: Fatal exception ]--- > --- > drivers/spi/spi.c | 33 ++++++++++++++++----------------- > 1 file changed, 16 insertions(+), 17 deletions(-) > > diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c > index 5becf6c2c409..e8c0a000ee19 100644 > --- a/drivers/spi/spi.c > +++ b/drivers/spi/spi.c > @@ -374,16 +374,7 @@ static int spi_uevent(struct device *dev, struct kobj_uevent_env *env) > return add_uevent_var(env, "MODALIAS=%s%s", SPI_MODULE_PREFIX, spi->modalias); > } > > -struct bus_type spi_bus_type = { > - .name = "spi", > - .dev_groups = spi_dev_groups, > - .match = spi_match_device, > - .uevent = spi_uevent, > -}; > -EXPORT_SYMBOL_GPL(spi_bus_type); > - > - > -static int spi_drv_probe(struct device *dev) > +static int spi_probe(struct device *dev) > { > const struct spi_driver *sdrv = to_spi_driver(dev->driver); > struct spi_device *spi = to_spi_device(dev); > @@ -414,7 +405,7 @@ static int spi_drv_probe(struct device *dev) > return ret; > } > > -static int spi_drv_remove(struct device *dev) > +static int spi_remove(struct device *dev) > { > const struct spi_driver *sdrv = to_spi_driver(dev->driver); > int ret = 0; > @@ -426,13 +417,25 @@ static int spi_drv_remove(struct device *dev) > return ret; > } > > -static void spi_drv_shutdown(struct device *dev) > +static void spi_shutdown(struct device *dev) > { > const struct spi_driver *sdrv = to_spi_driver(dev->driver); > > - sdrv->shutdown(to_spi_device(dev)); > + if (sdrv->shutdown) > + sdrv->shutdown(to_spi_device(dev)); > } In the above function dev->driver might be NULL, so its use in to_spi_driver() and sdrv->shutdown leads to NULL pointer dereference. I didn't check the details, but a simple check for NULL dev->driver and return is enough to fix this issue. I can send such fix if you want. > +struct bus_type spi_bus_type = { > + .name = "spi", > + .dev_groups = spi_dev_groups, > + .match = spi_match_device, > + .uevent = spi_uevent, > + .probe = spi_probe, > + .remove = spi_remove, > + .shutdown = spi_shutdown, > +}; > +EXPORT_SYMBOL_GPL(spi_bus_type); > + > /** > * __spi_register_driver - register a SPI driver > * @owner: owner module of the driver to register > @@ -445,10 +448,6 @@ int __spi_register_driver(struct module *owner, struct spi_driver *sdrv) > { > sdrv->driver.owner = owner; > sdrv->driver.bus = &spi_bus_type; > - sdrv->driver.probe = spi_drv_probe; > - sdrv->driver.remove = spi_drv_remove; > - if (sdrv->shutdown) > - sdrv->driver.shutdown = spi_drv_shutdown; > return driver_register(&sdrv->driver); > } > EXPORT_SYMBOL_GPL(__spi_register_driver); Best regards -- Marek Szyprowski, PhD Samsung R&D Institute Poland