| Message ID | 1613680181-31920-2-git-send-email-LinoSanfilippo@gmx.de |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [v6] tpm: fix reference counting for struct tpm_chip | expand |
On Thu, Feb 18, 2021 at 09:29:41PM +0100, Lino Sanfilippo wrote: > From: Lino Sanfilippo <l.sanfilippo@kunbus.com> > > The following sequence of operations results in a refcount warning: > > 1. Open device /dev/tpmrm. > 2. Remove module tpm_tis_spi. > 3. Write a TPM command to the file descriptor opened at step 1. > > ------------[ cut here ]------------ > WARNING: CPU: 3 PID: 1161 at lib/refcount.c:25 kobject_get+0xa0/0xa4 > refcount_t: addition on 0; use-after-free. > Modules linked in: tpm_tis_spi tpm_tis_core tpm mdio_bcm_unimac brcmfmac > sha256_generic libsha256 sha256_arm hci_uart btbcm bluetooth cfg80211 vc4 > brcmutil ecdh_generic ecc snd_soc_core crc32_arm_ce libaes > raspberrypi_hwmon ac97_bus snd_pcm_dmaengine bcm2711_thermal snd_pcm > snd_timer genet snd phy_generic soundcore [last unloaded: spi_bcm2835] > CPU: 3 PID: 1161 Comm: hold_open Not tainted 5.10.0ls-main-dirty #2 > Hardware name: BCM2711 > [<c0410c3c>] (unwind_backtrace) from [<c040b580>] (show_stack+0x10/0x14) > [<c040b580>] (show_stack) from [<c1092174>] (dump_stack+0xc4/0xd8) > [<c1092174>] (dump_stack) from [<c0445a30>] (__warn+0x104/0x108) > [<c0445a30>] (__warn) from [<c0445aa8>] (warn_slowpath_fmt+0x74/0xb8) > [<c0445aa8>] (warn_slowpath_fmt) from [<c08435d0>] (kobject_get+0xa0/0xa4) > [<c08435d0>] (kobject_get) from [<bf0a715c>] (tpm_try_get_ops+0x14/0x54 [tpm]) > [<bf0a715c>] (tpm_try_get_ops [tpm]) from [<bf0a7d6c>] (tpm_common_write+0x38/0x60 [tpm]) > [<bf0a7d6c>] (tpm_common_write [tpm]) from [<c05a7ac0>] (vfs_write+0xc4/0x3c0) > [<c05a7ac0>] (vfs_write) from [<c05a7ee4>] (ksys_write+0x58/0xcc) > [<c05a7ee4>] (ksys_write) from [<c04001a0>] (ret_fast_syscall+0x0/0x4c) > Exception stack(0xc226bfa8 to 0xc226bff0) > bfa0: 00000000 000105b4 00000003 beafe664 00000014 00000000 > bfc0: 00000000 000105b4 000103f8 00000004 00000000 00000000 b6f9c000 beafe684 > bfe0: 0000006c beafe648 0001056c b6eb6944 > ---[ end trace d4b8409def9b8b1f ]--- > > The reason for this warning is the attempt to get the chip->dev reference > in tpm_common_write() although the reference counter is already zero. > > Since commit 8979b02aaf1d ("tpm: Fix reference count to main device") the > extra reference used to prevent a premature zero counter is never taken, > because the required TPM_CHIP_FLAG_TPM2 flag is never set. > > Fix this by moving the TPM 2 character device handling from > tpm_chip_alloc() to tpm_add_char_device() which is called at a later point > in time when the flag has been set in case of TPM2. > > Commit fdc915f7f719 ("tpm: expose spaces via a device link /dev/tpmrm<n>") > already introduced function tpm_devs_release() to release the extra > reference but did not implement the required put on chip->devs that results > in the call of this function. > > Fix this by putting chip->devs in tpm_chip_unregister(). > > Finally move the new implementation for the TPM 2 handling into a new > function to avoid multiple checks for the TPM_CHIP_FLAG_TPM2 flag in the > good case and error cases. > > Cc: stable@vger.kernel.org > Fixes: fdc915f7f719 ("tpm: expose spaces via a device link /dev/tpmrm<n>") > Fixes: 8979b02aaf1d ("tpm: Fix reference count to main device") > Co-developed-by: Jason Gunthorpe <jgg@ziepe.ca> > Signed-off-by: Jason Gunthorpe <jgg@ziepe.ca> > Signed-off-by: Lino Sanfilippo <l.sanfilippo@kunbus.com> > --- > drivers/char/tpm/tpm-chip.c | 48 ++++++++----------------------------- > drivers/char/tpm/tpm.h | 1 + > drivers/char/tpm/tpm2-space.c | 55 +++++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 66 insertions(+), 38 deletions(-) > > diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c > index ddaeceb..ae6e414 100644 > --- a/drivers/char/tpm/tpm-chip.c > +++ b/drivers/char/tpm/tpm-chip.c > @@ -274,14 +274,6 @@ static void tpm_dev_release(struct device *dev) > kfree(chip); > } > > -static void tpm_devs_release(struct device *dev) > -{ > - struct tpm_chip *chip = container_of(dev, struct tpm_chip, devs); > - > - /* release the master device reference */ > - put_device(&chip->dev); > -} > - > /** > * tpm_class_shutdown() - prepare the TPM device for loss of power. > * @dev: device to which the chip is associated. > @@ -344,7 +336,6 @@ struct tpm_chip *tpm_chip_alloc(struct device *pdev, > chip->dev_num = rc; > > device_initialize(&chip->dev); > - device_initialize(&chip->devs); > > chip->dev.class = tpm_class; > chip->dev.class->shutdown_pre = tpm_class_shutdown; > @@ -352,39 +343,20 @@ struct tpm_chip *tpm_chip_alloc(struct device *pdev, > chip->dev.parent = pdev; > chip->dev.groups = chip->groups; > > - chip->devs.parent = pdev; > - chip->devs.class = tpmrm_class; > - chip->devs.release = tpm_devs_release; > - /* get extra reference on main device to hold on > - * behalf of devs. This holds the chip structure > - * while cdevs is in use. The corresponding put > - * is in the tpm_devs_release (TPM2 only) > - */ > - if (chip->flags & TPM_CHIP_FLAG_TPM2) > - get_device(&chip->dev); > - > if (chip->dev_num == 0) > chip->dev.devt = MKDEV(MISC_MAJOR, TPM_MINOR); > else > chip->dev.devt = MKDEV(MAJOR(tpm_devt), chip->dev_num); > > - chip->devs.devt = > - MKDEV(MAJOR(tpm_devt), chip->dev_num + TPM_NUM_DEVICES); > - > rc = dev_set_name(&chip->dev, "tpm%d", chip->dev_num); > if (rc) > goto out; > - rc = dev_set_name(&chip->devs, "tpmrm%d", chip->dev_num); > - if (rc) > - goto out; > > if (!pdev) > chip->flags |= TPM_CHIP_FLAG_VIRTUAL; > > cdev_init(&chip->cdev, &tpm_fops); > - cdev_init(&chip->cdevs, &tpmrm_fops); > chip->cdev.owner = THIS_MODULE; > - chip->cdevs.owner = THIS_MODULE; > > rc = tpm2_init_space(&chip->work_space, TPM2_SPACE_BUFFER_SIZE); > if (rc) { > @@ -396,7 +368,6 @@ struct tpm_chip *tpm_chip_alloc(struct device *pdev, > return chip; > > out: > - put_device(&chip->devs); > put_device(&chip->dev); > return ERR_PTR(rc); > } > @@ -445,14 +416,9 @@ static int tpm_add_char_device(struct tpm_chip *chip) > } > > if (chip->flags & TPM_CHIP_FLAG_TPM2) { > - rc = cdev_device_add(&chip->cdevs, &chip->devs); > - if (rc) { > - dev_err(&chip->devs, > - "unable to cdev_device_add() %s, major %d, minor %d, err=%d\n", > - dev_name(&chip->devs), MAJOR(chip->devs.devt), > - MINOR(chip->devs.devt), rc); > - return rc; > - } > + rc = tpm_devs_add(chip); > + if (rc) > + goto del_cdev; > } > > /* Make the chip available. */ > @@ -460,6 +426,10 @@ static int tpm_add_char_device(struct tpm_chip *chip) > idr_replace(&dev_nums_idr, chip, chip->dev_num); > mutex_unlock(&idr_lock); > > + return 0; > + > +del_cdev: > + cdev_device_del(&chip->cdev, &chip->dev); > return rc; > } > > @@ -640,8 +610,10 @@ void tpm_chip_unregister(struct tpm_chip *chip) > if (IS_ENABLED(CONFIG_HW_RANDOM_TPM)) > hwrng_unregister(&chip->hwrng); > tpm_bios_log_teardown(chip); > - if (chip->flags & TPM_CHIP_FLAG_TPM2) > + if (chip->flags & TPM_CHIP_FLAG_TPM2) { > cdev_device_del(&chip->cdevs, &chip->devs); > + put_device(&chip->devs); > + } > tpm_del_char_device(chip); > } > EXPORT_SYMBOL_GPL(tpm_chip_unregister); > diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h > index 947d1db..ac4b2dc 100644 > --- a/drivers/char/tpm/tpm.h > +++ b/drivers/char/tpm/tpm.h > @@ -238,6 +238,7 @@ int tpm2_prepare_space(struct tpm_chip *chip, struct tpm_space *space, u8 *cmd, > size_t cmdsiz); > int tpm2_commit_space(struct tpm_chip *chip, struct tpm_space *space, void *buf, > size_t *bufsiz); > +int tpm_devs_add(struct tpm_chip *chip); > > void tpm_bios_log_setup(struct tpm_chip *chip); > void tpm_bios_log_teardown(struct tpm_chip *chip); > diff --git a/drivers/char/tpm/tpm2-space.c b/drivers/char/tpm/tpm2-space.c > index 784b8b3..6d17f77 100644 > --- a/drivers/char/tpm/tpm2-space.c > +++ b/drivers/char/tpm/tpm2-space.c > @@ -571,3 +571,58 @@ int tpm2_commit_space(struct tpm_chip *chip, struct tpm_space *space, > dev_err(&chip->dev, "%s: error %d\n", __func__, rc); > return rc; > } > + > +/* > + * Put the reference to the main device. > + */ > +static void tpm_devs_release(struct device *dev) > +{ > + struct tpm_chip *chip = container_of(dev, struct tpm_chip, devs); > + > + /* release the master device reference */ > + put_device(&chip->dev); > +} > + > +/* > + * Add a device file to expose TPM spaces. Also take a reference to the > + * main device. > + */ > +int tpm_devs_add(struct tpm_chip *chip) > +{ > + int rc; > + > + device_initialize(&chip->devs); > + chip->devs.parent = chip->dev.parent; > + chip->devs.class = tpmrm_class; > + > + /* > + * Get extra reference on main device to hold on behalf of devs. > + * This holds the chip structure while cdevs is in use. The > + * corresponding put is in the tpm_devs_release. > + */ > + get_device(&chip->dev); > + chip->devs.release = tpm_devs_release; > + chip->devs.devt = MKDEV(MAJOR(tpm_devt), chip->dev_num + TPM_NUM_DEVICES); > + cdev_init(&chip->cdevs, &tpmrm_fops); > + chip->cdevs.owner = THIS_MODULE; > + > + rc = dev_set_name(&chip->devs, "tpmrm%d", chip->dev_num); > + if (rc) > + goto out_put_devs; > + > + rc = cdev_device_add(&chip->cdevs, &chip->devs); > + if (rc) { > + dev_err(&chip->devs, > + "unable to cdev_device_add() %s, major %d, minor %d, err=%d\n", > + dev_name(&chip->devs), MAJOR(chip->devs.devt), > + MINOR(chip->devs.devt), rc); > + goto out_put_devs; > + } > + > + return 0; > + > +out_put_devs: A nit: 1. You have already del_cdev: 2. Here you use a differing convention with out prefix. I'd suggest that you put err_ to both: 1. err_del_cdev 2. err_put_devs It's quite coherent what we have already: linux-tpmdd on next took 8s ❯ git grep "^err_.*" drivers/char/tpm/ | wc -l 17 > + put_device(&chip->devs); > + > + return rc; > +} > -- > 2.7.4 > Other than that, no complains. /Jarkko
On Fri, Feb 19, 2021 at 11:13:45AM +0200, Jarkko Sakkinen wrote: > On Thu, Feb 18, 2021 at 09:29:41PM +0100, Lino Sanfilippo wrote: > > From: Lino Sanfilippo <l.sanfilippo@kunbus.com> > > > > The following sequence of operations results in a refcount warning: > > > > 1. Open device /dev/tpmrm. > > 2. Remove module tpm_tis_spi. > > 3. Write a TPM command to the file descriptor opened at step 1. > > > > ------------[ cut here ]------------ > > WARNING: CPU: 3 PID: 1161 at lib/refcount.c:25 kobject_get+0xa0/0xa4 > > refcount_t: addition on 0; use-after-free. > > Modules linked in: tpm_tis_spi tpm_tis_core tpm mdio_bcm_unimac brcmfmac > > sha256_generic libsha256 sha256_arm hci_uart btbcm bluetooth cfg80211 vc4 > > brcmutil ecdh_generic ecc snd_soc_core crc32_arm_ce libaes > > raspberrypi_hwmon ac97_bus snd_pcm_dmaengine bcm2711_thermal snd_pcm > > snd_timer genet snd phy_generic soundcore [last unloaded: spi_bcm2835] > > CPU: 3 PID: 1161 Comm: hold_open Not tainted 5.10.0ls-main-dirty #2 > > Hardware name: BCM2711 > > [<c0410c3c>] (unwind_backtrace) from [<c040b580>] (show_stack+0x10/0x14) > > [<c040b580>] (show_stack) from [<c1092174>] (dump_stack+0xc4/0xd8) > > [<c1092174>] (dump_stack) from [<c0445a30>] (__warn+0x104/0x108) > > [<c0445a30>] (__warn) from [<c0445aa8>] (warn_slowpath_fmt+0x74/0xb8) > > [<c0445aa8>] (warn_slowpath_fmt) from [<c08435d0>] (kobject_get+0xa0/0xa4) > > [<c08435d0>] (kobject_get) from [<bf0a715c>] (tpm_try_get_ops+0x14/0x54 [tpm]) > > [<bf0a715c>] (tpm_try_get_ops [tpm]) from [<bf0a7d6c>] (tpm_common_write+0x38/0x60 [tpm]) > > [<bf0a7d6c>] (tpm_common_write [tpm]) from [<c05a7ac0>] (vfs_write+0xc4/0x3c0) > > [<c05a7ac0>] (vfs_write) from [<c05a7ee4>] (ksys_write+0x58/0xcc) > > [<c05a7ee4>] (ksys_write) from [<c04001a0>] (ret_fast_syscall+0x0/0x4c) > > Exception stack(0xc226bfa8 to 0xc226bff0) > > bfa0: 00000000 000105b4 00000003 beafe664 00000014 00000000 > > bfc0: 00000000 000105b4 000103f8 00000004 00000000 00000000 b6f9c000 beafe684 > > bfe0: 0000006c beafe648 0001056c b6eb6944 > > ---[ end trace d4b8409def9b8b1f ]--- > > > > The reason for this warning is the attempt to get the chip->dev reference > > in tpm_common_write() although the reference counter is already zero. > > > > Since commit 8979b02aaf1d ("tpm: Fix reference count to main device") the > > extra reference used to prevent a premature zero counter is never taken, > > because the required TPM_CHIP_FLAG_TPM2 flag is never set. > > > > Fix this by moving the TPM 2 character device handling from > > tpm_chip_alloc() to tpm_add_char_device() which is called at a later point > > in time when the flag has been set in case of TPM2. > > > > Commit fdc915f7f719 ("tpm: expose spaces via a device link /dev/tpmrm<n>") > > already introduced function tpm_devs_release() to release the extra > > reference but did not implement the required put on chip->devs that results > > in the call of this function. > > > > Fix this by putting chip->devs in tpm_chip_unregister(). > > > > Finally move the new implementation for the TPM 2 handling into a new > > function to avoid multiple checks for the TPM_CHIP_FLAG_TPM2 flag in the > > good case and error cases. > > > > Cc: stable@vger.kernel.org > > Fixes: fdc915f7f719 ("tpm: expose spaces via a device link /dev/tpmrm<n>") > > Fixes: 8979b02aaf1d ("tpm: Fix reference count to main device") > > Co-developed-by: Jason Gunthorpe <jgg@ziepe.ca> > > Signed-off-by: Jason Gunthorpe <jgg@ziepe.ca> > > Signed-off-by: Lino Sanfilippo <l.sanfilippo@kunbus.com> > > --- > > drivers/char/tpm/tpm-chip.c | 48 ++++++++----------------------------- > > drivers/char/tpm/tpm.h | 1 + > > drivers/char/tpm/tpm2-space.c | 55 +++++++++++++++++++++++++++++++++++++++++++ > > 3 files changed, 66 insertions(+), 38 deletions(-) > > > > diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c > > index ddaeceb..ae6e414 100644 > > --- a/drivers/char/tpm/tpm-chip.c > > +++ b/drivers/char/tpm/tpm-chip.c > > @@ -274,14 +274,6 @@ static void tpm_dev_release(struct device *dev) > > kfree(chip); > > } > > > > -static void tpm_devs_release(struct device *dev) > > -{ > > - struct tpm_chip *chip = container_of(dev, struct tpm_chip, devs); > > - > > - /* release the master device reference */ > > - put_device(&chip->dev); > > -} > > - > > /** > > * tpm_class_shutdown() - prepare the TPM device for loss of power. > > * @dev: device to which the chip is associated. > > @@ -344,7 +336,6 @@ struct tpm_chip *tpm_chip_alloc(struct device *pdev, > > chip->dev_num = rc; > > > > device_initialize(&chip->dev); > > - device_initialize(&chip->devs); > > > > chip->dev.class = tpm_class; > > chip->dev.class->shutdown_pre = tpm_class_shutdown; > > @@ -352,39 +343,20 @@ struct tpm_chip *tpm_chip_alloc(struct device *pdev, > > chip->dev.parent = pdev; > > chip->dev.groups = chip->groups; > > > > - chip->devs.parent = pdev; > > - chip->devs.class = tpmrm_class; > > - chip->devs.release = tpm_devs_release; > > - /* get extra reference on main device to hold on > > - * behalf of devs. This holds the chip structure > > - * while cdevs is in use. The corresponding put > > - * is in the tpm_devs_release (TPM2 only) > > - */ > > - if (chip->flags & TPM_CHIP_FLAG_TPM2) > > - get_device(&chip->dev); > > - > > if (chip->dev_num == 0) > > chip->dev.devt = MKDEV(MISC_MAJOR, TPM_MINOR); > > else > > chip->dev.devt = MKDEV(MAJOR(tpm_devt), chip->dev_num); > > > > - chip->devs.devt = > > - MKDEV(MAJOR(tpm_devt), chip->dev_num + TPM_NUM_DEVICES); > > - > > rc = dev_set_name(&chip->dev, "tpm%d", chip->dev_num); > > if (rc) > > goto out; > > - rc = dev_set_name(&chip->devs, "tpmrm%d", chip->dev_num); > > - if (rc) > > - goto out; > > > > if (!pdev) > > chip->flags |= TPM_CHIP_FLAG_VIRTUAL; > > > > cdev_init(&chip->cdev, &tpm_fops); > > - cdev_init(&chip->cdevs, &tpmrm_fops); > > chip->cdev.owner = THIS_MODULE; > > - chip->cdevs.owner = THIS_MODULE; > > > > rc = tpm2_init_space(&chip->work_space, TPM2_SPACE_BUFFER_SIZE); > > if (rc) { > > @@ -396,7 +368,6 @@ struct tpm_chip *tpm_chip_alloc(struct device *pdev, > > return chip; > > > > out: > > - put_device(&chip->devs); > > put_device(&chip->dev); > > return ERR_PTR(rc); > > } > > @@ -445,14 +416,9 @@ static int tpm_add_char_device(struct tpm_chip *chip) > > } > > > > if (chip->flags & TPM_CHIP_FLAG_TPM2) { > > - rc = cdev_device_add(&chip->cdevs, &chip->devs); > > - if (rc) { > > - dev_err(&chip->devs, > > - "unable to cdev_device_add() %s, major %d, minor %d, err=%d\n", > > - dev_name(&chip->devs), MAJOR(chip->devs.devt), > > - MINOR(chip->devs.devt), rc); > > - return rc; > > - } > > + rc = tpm_devs_add(chip); > > + if (rc) > > + goto del_cdev; > > } > > > > /* Make the chip available. */ > > @@ -460,6 +426,10 @@ static int tpm_add_char_device(struct tpm_chip *chip) > > idr_replace(&dev_nums_idr, chip, chip->dev_num); > > mutex_unlock(&idr_lock); > > > > + return 0; > > + > > +del_cdev: > > + cdev_device_del(&chip->cdev, &chip->dev); > > return rc; > > } > > > > @@ -640,8 +610,10 @@ void tpm_chip_unregister(struct tpm_chip *chip) > > if (IS_ENABLED(CONFIG_HW_RANDOM_TPM)) > > hwrng_unregister(&chip->hwrng); > > tpm_bios_log_teardown(chip); > > - if (chip->flags & TPM_CHIP_FLAG_TPM2) > > + if (chip->flags & TPM_CHIP_FLAG_TPM2) { > > cdev_device_del(&chip->cdevs, &chip->devs); > > + put_device(&chip->devs); > > + } > > tpm_del_char_device(chip); > > } > > EXPORT_SYMBOL_GPL(tpm_chip_unregister); > > diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h > > index 947d1db..ac4b2dc 100644 > > --- a/drivers/char/tpm/tpm.h > > +++ b/drivers/char/tpm/tpm.h > > @@ -238,6 +238,7 @@ int tpm2_prepare_space(struct tpm_chip *chip, struct tpm_space *space, u8 *cmd, > > size_t cmdsiz); > > int tpm2_commit_space(struct tpm_chip *chip, struct tpm_space *space, void *buf, > > size_t *bufsiz); > > +int tpm_devs_add(struct tpm_chip *chip); > > > > void tpm_bios_log_setup(struct tpm_chip *chip); > > void tpm_bios_log_teardown(struct tpm_chip *chip); > > diff --git a/drivers/char/tpm/tpm2-space.c b/drivers/char/tpm/tpm2-space.c > > index 784b8b3..6d17f77 100644 > > --- a/drivers/char/tpm/tpm2-space.c > > +++ b/drivers/char/tpm/tpm2-space.c > > @@ -571,3 +571,58 @@ int tpm2_commit_space(struct tpm_chip *chip, struct tpm_space *space, > > dev_err(&chip->dev, "%s: error %d\n", __func__, rc); > > return rc; > > } > > + > > +/* > > + * Put the reference to the main device. > > + */ > > +static void tpm_devs_release(struct device *dev) > > +{ > > + struct tpm_chip *chip = container_of(dev, struct tpm_chip, devs); > > + > > + /* release the master device reference */ > > + put_device(&chip->dev); > > +} > > + > > +/* > > + * Add a device file to expose TPM spaces. Also take a reference to the > > + * main device. > > + */ > > +int tpm_devs_add(struct tpm_chip *chip) > > +{ > > + int rc; > > + > > + device_initialize(&chip->devs); > > + chip->devs.parent = chip->dev.parent; > > + chip->devs.class = tpmrm_class; > > + > > + /* > > + * Get extra reference on main device to hold on behalf of devs. > > + * This holds the chip structure while cdevs is in use. The > > + * corresponding put is in the tpm_devs_release. > > + */ > > + get_device(&chip->dev); > > + chip->devs.release = tpm_devs_release; > > + chip->devs.devt = MKDEV(MAJOR(tpm_devt), chip->dev_num + TPM_NUM_DEVICES); > > + cdev_init(&chip->cdevs, &tpmrm_fops); > > + chip->cdevs.owner = THIS_MODULE; > > + > > + rc = dev_set_name(&chip->devs, "tpmrm%d", chip->dev_num); > > + if (rc) > > + goto out_put_devs; > > + > > + rc = cdev_device_add(&chip->cdevs, &chip->devs); > > + if (rc) { > > + dev_err(&chip->devs, > > + "unable to cdev_device_add() %s, major %d, minor %d, err=%d\n", > > + dev_name(&chip->devs), MAJOR(chip->devs.devt), > > + MINOR(chip->devs.devt), rc); > > + goto out_put_devs; > > + } > > + > > + return 0; > > + > > +out_put_devs: > > A nit: > > 1. You have already del_cdev: > 2. Here you use a differing convention with out prefix. > > I'd suggest that you put err_ to both: > > 1. err_del_cdev > 2. err_put_devs > > It's quite coherent what we have already: > > linux-tpmdd on next took 8s > ❯ git grep "^err_.*" drivers/char/tpm/ | wc -l > 17 I guess there's some ambiguity with this, but IMHO makes a lot of sense for code blocks *only* executed as an exception handler. /Jarkko
Hi, On 19.02.21 at 10:13, Jarkko Sakkinen wrote: >> + rc = cdev_device_add(&chip->cdevs, &chip->devs); >> + if (rc) { >> + dev_err(&chip->devs, >> + "unable to cdev_device_add() %s, major %d, minor %d, err=%d\n", >> + dev_name(&chip->devs), MAJOR(chip->devs.devt), >> + MINOR(chip->devs.devt), rc); >> + goto out_put_devs; >> + } >> + >> + return 0; >> + >> +out_put_devs: > > A nit: > > 1. You have already del_cdev: > 2. Here you use a differing convention with out prefix. > > I'd suggest that you put err_ to both: > > 1. err_del_cdev > 2. err_put_devs > > It's quite coherent what we have already: > > linux-tpmdd on next took 8s > ❯ git grep "^err_.*" drivers/char/tpm/ | wc -l > 17 > The label del_cdev is indeed a bit inconsistent with the rest of the code. But AFAICS out_put_devs is not: 1. all labels in tpm2-space.c start with out_ 2. there are more hits for out_ across the whole TPM code (i.e. with the same command you used above I get 31 hits for _out) than for err_. I suggest to rename del_cdev to something like out_del_cdev or maybe out_cdev which seems to be even closer to the existing naming scheme for labels. Regards, Lino
On Sun, Feb 21, 2021 at 11:19:28AM +0100, Lino Sanfilippo wrote: > > Hi, > > On 19.02.21 at 10:13, Jarkko Sakkinen wrote: > > >> + rc = cdev_device_add(&chip->cdevs, &chip->devs); > >> + if (rc) { > >> + dev_err(&chip->devs, > >> + "unable to cdev_device_add() %s, major %d, minor %d, err=%d\n", > >> + dev_name(&chip->devs), MAJOR(chip->devs.devt), > >> + MINOR(chip->devs.devt), rc); > >> + goto out_put_devs; > >> + } > >> + > >> + return 0; > >> + > >> +out_put_devs: > > > > A nit: > > > > 1. You have already del_cdev: > > 2. Here you use a differing convention with out prefix. > > > > I'd suggest that you put err_ to both: > > > > 1. err_del_cdev > > 2. err_put_devs > > > > It's quite coherent what we have already: > > > > linux-tpmdd on next took 8s > > ❯ git grep "^err_.*" drivers/char/tpm/ | wc -l > > 17 > > > > > The label del_cdev is indeed a bit inconsistent with the rest of the code. > But AFAICS out_put_devs is not: > 1. all labels in tpm2-space.c start with out_ > 2. there are more hits for out_ across the whole TPM code (i.e. with the same command > you used above I get 31 hits for _out) than for err_. > > I suggest to rename del_cdev to something like out_del_cdev or maybe out_cdev which > seems to be even closer to the existing naming scheme for labels. OK, that makes sense, thanks! > Regards, > Lino /Jarkko
On Sun, Feb 21, 2021 at 11:19:28AM +0100, Lino Sanfilippo wrote: > > Hi, > > On 19.02.21 at 10:13, Jarkko Sakkinen wrote: > > >> + rc = cdev_device_add(&chip->cdevs, &chip->devs); > >> + if (rc) { > >> + dev_err(&chip->devs, > >> + "unable to cdev_device_add() %s, major %d, minor %d, err=%d\n", > >> + dev_name(&chip->devs), MAJOR(chip->devs.devt), > >> + MINOR(chip->devs.devt), rc); > >> + goto out_put_devs; > >> + } > >> + > >> + return 0; > >> + > >> +out_put_devs: > > > > A nit: > > > > 1. You have already del_cdev: > > 2. Here you use a differing convention with out prefix. > > > > I'd suggest that you put err_ to both: > > > > 1. err_del_cdev > > 2. err_put_devs > > > > It's quite coherent what we have already: > > > > linux-tpmdd on next took 8s > > ❯ git grep "^err_.*" drivers/char/tpm/ | wc -l > > 17 > > > > > The label del_cdev is indeed a bit inconsistent with the rest of the code. > But AFAICS out_put_devs is not: > 1. all labels in tpm2-space.c start with out_ > 2. there are more hits for out_ across the whole TPM code (i.e. with the same command > you used above I get 31 hits for _out) than for err_. > > I suggest to rename del_cdev to something like out_del_cdev or maybe out_cdev which > seems to be even closer to the existing naming scheme for labels. Generally, I'd prefer the following pattern: out: /* out for success path if needed */ return 0; err_foo: err_bar: return ret; Existing naming scheme is not something to hang into, and I don't care to preserve it. > Regards, > Lino /Jarkko
diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c index ddaeceb..ae6e414 100644 --- a/drivers/char/tpm/tpm-chip.c +++ b/drivers/char/tpm/tpm-chip.c @@ -274,14 +274,6 @@ static void tpm_dev_release(struct device *dev) kfree(chip); } -static void tpm_devs_release(struct device *dev) -{ - struct tpm_chip *chip = container_of(dev, struct tpm_chip, devs); - - /* release the master device reference */ - put_device(&chip->dev); -} - /** * tpm_class_shutdown() - prepare the TPM device for loss of power. * @dev: device to which the chip is associated. @@ -344,7 +336,6 @@ struct tpm_chip *tpm_chip_alloc(struct device *pdev, chip->dev_num = rc; device_initialize(&chip->dev); - device_initialize(&chip->devs); chip->dev.class = tpm_class; chip->dev.class->shutdown_pre = tpm_class_shutdown; @@ -352,39 +343,20 @@ struct tpm_chip *tpm_chip_alloc(struct device *pdev, chip->dev.parent = pdev; chip->dev.groups = chip->groups; - chip->devs.parent = pdev; - chip->devs.class = tpmrm_class; - chip->devs.release = tpm_devs_release; - /* get extra reference on main device to hold on - * behalf of devs. This holds the chip structure - * while cdevs is in use. The corresponding put - * is in the tpm_devs_release (TPM2 only) - */ - if (chip->flags & TPM_CHIP_FLAG_TPM2) - get_device(&chip->dev); - if (chip->dev_num == 0) chip->dev.devt = MKDEV(MISC_MAJOR, TPM_MINOR); else chip->dev.devt = MKDEV(MAJOR(tpm_devt), chip->dev_num); - chip->devs.devt = - MKDEV(MAJOR(tpm_devt), chip->dev_num + TPM_NUM_DEVICES); - rc = dev_set_name(&chip->dev, "tpm%d", chip->dev_num); if (rc) goto out; - rc = dev_set_name(&chip->devs, "tpmrm%d", chip->dev_num); - if (rc) - goto out; if (!pdev) chip->flags |= TPM_CHIP_FLAG_VIRTUAL; cdev_init(&chip->cdev, &tpm_fops); - cdev_init(&chip->cdevs, &tpmrm_fops); chip->cdev.owner = THIS_MODULE; - chip->cdevs.owner = THIS_MODULE; rc = tpm2_init_space(&chip->work_space, TPM2_SPACE_BUFFER_SIZE); if (rc) { @@ -396,7 +368,6 @@ struct tpm_chip *tpm_chip_alloc(struct device *pdev, return chip; out: - put_device(&chip->devs); put_device(&chip->dev); return ERR_PTR(rc); } @@ -445,14 +416,9 @@ static int tpm_add_char_device(struct tpm_chip *chip) } if (chip->flags & TPM_CHIP_FLAG_TPM2) { - rc = cdev_device_add(&chip->cdevs, &chip->devs); - if (rc) { - dev_err(&chip->devs, - "unable to cdev_device_add() %s, major %d, minor %d, err=%d\n", - dev_name(&chip->devs), MAJOR(chip->devs.devt), - MINOR(chip->devs.devt), rc); - return rc; - } + rc = tpm_devs_add(chip); + if (rc) + goto del_cdev; } /* Make the chip available. */ @@ -460,6 +426,10 @@ static int tpm_add_char_device(struct tpm_chip *chip) idr_replace(&dev_nums_idr, chip, chip->dev_num); mutex_unlock(&idr_lock); + return 0; + +del_cdev: + cdev_device_del(&chip->cdev, &chip->dev); return rc; } @@ -640,8 +610,10 @@ void tpm_chip_unregister(struct tpm_chip *chip) if (IS_ENABLED(CONFIG_HW_RANDOM_TPM)) hwrng_unregister(&chip->hwrng); tpm_bios_log_teardown(chip); - if (chip->flags & TPM_CHIP_FLAG_TPM2) + if (chip->flags & TPM_CHIP_FLAG_TPM2) { cdev_device_del(&chip->cdevs, &chip->devs); + put_device(&chip->devs); + } tpm_del_char_device(chip); } EXPORT_SYMBOL_GPL(tpm_chip_unregister); diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h index 947d1db..ac4b2dc 100644 --- a/drivers/char/tpm/tpm.h +++ b/drivers/char/tpm/tpm.h @@ -238,6 +238,7 @@ int tpm2_prepare_space(struct tpm_chip *chip, struct tpm_space *space, u8 *cmd, size_t cmdsiz); int tpm2_commit_space(struct tpm_chip *chip, struct tpm_space *space, void *buf, size_t *bufsiz); +int tpm_devs_add(struct tpm_chip *chip); void tpm_bios_log_setup(struct tpm_chip *chip); void tpm_bios_log_teardown(struct tpm_chip *chip); diff --git a/drivers/char/tpm/tpm2-space.c b/drivers/char/tpm/tpm2-space.c index 784b8b3..6d17f77 100644 --- a/drivers/char/tpm/tpm2-space.c +++ b/drivers/char/tpm/tpm2-space.c @@ -571,3 +571,58 @@ int tpm2_commit_space(struct tpm_chip *chip, struct tpm_space *space, dev_err(&chip->dev, "%s: error %d\n", __func__, rc); return rc; } + +/* + * Put the reference to the main device. + */ +static void tpm_devs_release(struct device *dev) +{ + struct tpm_chip *chip = container_of(dev, struct tpm_chip, devs); + + /* release the master device reference */ + put_device(&chip->dev); +} + +/* + * Add a device file to expose TPM spaces. Also take a reference to the + * main device. + */ +int tpm_devs_add(struct tpm_chip *chip) +{ + int rc; + + device_initialize(&chip->devs); + chip->devs.parent = chip->dev.parent; + chip->devs.class = tpmrm_class; + + /* + * Get extra reference on main device to hold on behalf of devs. + * This holds the chip structure while cdevs is in use. The + * corresponding put is in the tpm_devs_release. + */ + get_device(&chip->dev); + chip->devs.release = tpm_devs_release; + chip->devs.devt = MKDEV(MAJOR(tpm_devt), chip->dev_num + TPM_NUM_DEVICES); + cdev_init(&chip->cdevs, &tpmrm_fops); + chip->cdevs.owner = THIS_MODULE; + + rc = dev_set_name(&chip->devs, "tpmrm%d", chip->dev_num); + if (rc) + goto out_put_devs; + + rc = cdev_device_add(&chip->cdevs, &chip->devs); + if (rc) { + dev_err(&chip->devs, + "unable to cdev_device_add() %s, major %d, minor %d, err=%d\n", + dev_name(&chip->devs), MAJOR(chip->devs.devt), + MINOR(chip->devs.devt), rc); + goto out_put_devs; + } + + return 0; + +out_put_devs: + put_device(&chip->devs); + + return rc; +}