* [PATCH v7] TPM fixes @ 2021-02-21 23:19 Lino Sanfilippo 2021-02-21 23:19 ` [PATCH v7] tpm: fix reference counting for struct tpm_chip Lino Sanfilippo 0 siblings, 1 reply; 3+ messages in thread From: Lino Sanfilippo @ 2021-02-21 23:19 UTC (permalink / raw) To: peterhuewe, jarkko, jgg Cc: stefanb, James.Bottomley, David.Laight, linux-integrity, linux-kernel, LinoSanfilippo This patch fixes a reference count issue in the TPM core code. Changes in v7: - adjust naming of jump labels to fit better the used label naming scheme Changes in v6: - rename function tpm2_add_device() to tpm_devs_add() as requested by Jarko - add function descriptions - fix source code formatting Changes in v5: - move function tpm_add_tpm2_char_device() to tpm2-space.c and rename it to tpm2_add_device() as requested by Jarko - put "cc" tag before all other tags - ensure that the error path in tpm2_add_device() always calls the release() function of chip->devs as requested by Jason - reformat a code line as suggested by David Laight Changes in v4: - drop patch 2 (tpm: in tpm2_del_space check if ops pointer is still valid) since James Bottomley offered a cleaner solution for this - reimplement patch 1 to setup the /dev/tpmrm device only in case of TPM2 and avoid the installation of another action handler. This is based on a suggestion and basic implementation done by Jason Gunthorpe. - added tag to CC stable Changes in v3: - drop the patch that introduces the new function tpm_chip_free() - rework the commit messages for the patches (style, typos, etc.) - add fixes tag to patch 2 - add James Bottomley to cc list - add stable mailing list to cc list Changes in v2: - drop the patch that erroneously cleaned up after failed installation of an action handler in tpmm_chip_alloc() (pointed out by Jarkko Sakkinen) - make the commit message for patch 1 more detailed - add fixes tags and kernel logs Lino Sanfilippo (1): tpm: fix reference counting for struct tpm_chip 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(-) -- 2.7.4 ^ permalink raw reply [flat|nested] 3+ messages in thread
* [PATCH v7] tpm: fix reference counting for struct tpm_chip 2021-02-21 23:19 [PATCH v7] TPM fixes Lino Sanfilippo @ 2021-02-21 23:19 ` Lino Sanfilippo 2021-02-24 16:46 ` Jarkko Sakkinen 0 siblings, 1 reply; 3+ messages in thread From: Lino Sanfilippo @ 2021-02-21 23:19 UTC (permalink / raw) To: peterhuewe, jarkko, jgg Cc: stefanb, James.Bottomley, David.Laight, linux-integrity, linux-kernel, LinoSanfilippo, Lino Sanfilippo, stable 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..3f59f09 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 out_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; + +out_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..2f8bb3e 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_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_devs; + } + + return 0; + +out_devs: + put_device(&chip->devs); + + return rc; +} -- 2.7.4 ^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH v7] tpm: fix reference counting for struct tpm_chip 2021-02-21 23:19 ` [PATCH v7] tpm: fix reference counting for struct tpm_chip Lino Sanfilippo @ 2021-02-24 16:46 ` Jarkko Sakkinen 0 siblings, 0 replies; 3+ messages in thread From: Jarkko Sakkinen @ 2021-02-24 16:46 UTC (permalink / raw) To: Lino Sanfilippo Cc: peterhuewe, jgg, stefanb, James.Bottomley, David.Laight, linux-integrity, linux-kernel, Lino Sanfilippo, stable On Mon, Feb 22, 2021 at 12:19:27AM +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..3f59f09 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 out_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; > + > +out_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..2f8bb3e 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_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_devs; > + } > + > + return 0; > + > +out_devs: > + put_device(&chip->devs); > + > + return rc; Yeah, for these the err_ prefix would make more sense. > +} > -- > 2.7.4 > /Jarkko ^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2021-02-24 16:48 UTC | newest] Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2021-02-21 23:19 [PATCH v7] TPM fixes Lino Sanfilippo 2021-02-21 23:19 ` [PATCH v7] tpm: fix reference counting for struct tpm_chip Lino Sanfilippo 2021-02-24 16:46 ` Jarkko Sakkinen
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