Messages in this thread Patch in this message | | | From | Rajiv Andrade <> | Subject | [PATCH 3/5] TPM rcu locking | Date | Fri, 3 Oct 2008 13:30:08 -0300 |
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Protects tpm_chip_list when transversing it.
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com> Signed-off-by: Rajiv Andrade <srajiv@linux.vnet.ibm.com> --- drivers/char/tpm/tpm.c | 57 +++++++++++++++++------------------------------ 1 files changed, 21 insertions(+), 36 deletions(-)
diff --git a/drivers/char/tpm/tpm.c b/drivers/char/tpm/tpm.c index dfd4e7f..24fb7ab 100644 --- a/drivers/char/tpm/tpm.c +++ b/drivers/char/tpm/tpm.c @@ -961,33 +961,28 @@ EXPORT_SYMBOL_GPL(tpm_store_cancel); */ int tpm_open(struct inode *inode, struct file *file) { - int rc = 0, minor = iminor(inode); + int minor = iminor(inode); struct tpm_chip *chip = NULL, *pos; - spin_lock(&driver_lock); - - list_for_each_entry(pos, &tpm_chip_list, list) { + rcu_read_lock(); + list_for_each_entry_rcu(pos, &tpm_chip_list, list) { if (pos->vendor.miscdev.minor == minor) { chip = pos; + get_device(chip->dev); break; } } + rcu_read_unlock(); - if (chip == NULL) { - rc = -ENODEV; - goto err_out; - } + if (!chip) + return -ENODEV; if (test_and_set_bit(0, &chip->is_open)) { dev_dbg(chip->dev, "Another process owns this TPM\n"); - rc = -EBUSY; - goto err_out; + put_device(chip->dev); + return -EBUSY; } - get_device(chip->dev); - - spin_unlock(&driver_lock); - chip->data_buffer = kmalloc(TPM_BUFSIZE * sizeof(u8), GFP_KERNEL); if (chip->data_buffer == NULL) { clear_bit(0, &chip->is_open); @@ -999,26 +994,23 @@ int tpm_open(struct inode *inode, struct file *file) file->private_data = chip; return 0; - -err_out: - spin_unlock(&driver_lock); - return rc; } EXPORT_SYMBOL_GPL(tpm_open); +/* + * Called on file close + */ int tpm_release(struct inode *inode, struct file *file) { struct tpm_chip *chip = file->private_data; flush_scheduled_work(); - spin_lock(&driver_lock); file->private_data = NULL; del_singleshot_timer_sync(&chip->user_read_timer); atomic_set(&chip->data_pending, 0); + kfree(chip->data_buffer); clear_bit(0, &chip->is_open); put_device(chip->dev); - kfree(chip->data_buffer); - spin_unlock(&driver_lock); return 0; } EXPORT_SYMBOL_GPL(tpm_release); @@ -1092,13 +1084,11 @@ void tpm_remove_hardware(struct device *dev) } spin_lock(&driver_lock); - - list_del(&chip->list); - + list_del_rcu(&chip->list); spin_unlock(&driver_lock); + synchronize_rcu(); misc_deregister(&chip->vendor.miscdev); - sysfs_remove_group(&dev->kobj, chip->vendor.attr_group); tpm_bios_log_teardown(chip->bios_dir); @@ -1146,8 +1136,7 @@ EXPORT_SYMBOL_GPL(tpm_pm_resume); /* * Once all references to platform device are down to 0, * release all allocated structures. - * In case vendor provided release function, - * call it too. + * In case vendor provided release function, call it too. */ static void tpm_dev_release(struct device *dev) { @@ -1155,7 +1144,6 @@ static void tpm_dev_release(struct device *dev) if (chip->vendor.release) chip->vendor.release(dev); - chip->release(dev); clear_bit(chip->dev_num, dev_mask); @@ -1170,8 +1158,8 @@ static void tpm_dev_release(struct device *dev) * upon errant exit from this function specific probe function should call * pci_disable_device */ -struct tpm_chip *tpm_register_hardware(struct device *dev, const struct tpm_vendor_specific - *entry) +struct tpm_chip *tpm_register_hardware(struct device *dev, + const struct tpm_vendor_specific *entry) { #define DEVNAME_SIZE 7 @@ -1230,12 +1218,6 @@ struct tpm_chip *tpm_register_hardware(struct device *dev, const struct tpm_vend return NULL; } - spin_lock(&driver_lock); - - list_add(&chip->list, &tpm_chip_list); - - spin_unlock(&driver_lock); - if (sysfs_create_group(&dev->kobj, chip->vendor.attr_group)) { list_del(&chip->list); misc_deregister(&chip->vendor.miscdev); @@ -1245,6 +1227,9 @@ struct tpm_chip *tpm_register_hardware(struct device *dev, const struct tpm_vend chip->bios_dir = tpm_bios_log_setup(devname); + /* Make chip available */ + list_add_rcu(&chip->list, &tpm_chip_list); + return chip; } EXPORT_SYMBOL_GPL(tpm_register_hardware); -- 1.5.6.3
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