Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754089AbYJFOaT (ORCPT ); Mon, 6 Oct 2008 10:30:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752486AbYJFOaG (ORCPT ); Mon, 6 Oct 2008 10:30:06 -0400 Received: from igw1.br.ibm.com ([32.104.18.24]:42209 "EHLO igw1.br.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752412AbYJFOaE (ORCPT ); Mon, 6 Oct 2008 10:30:04 -0400 Subject: Re: [PATCH 3/5][resubmit][FIXED] TPM: rcu locking From: Rajiv Andrade To: "Serge E. Hallyn" Cc: linux-kernel@vger.kernel.org, zohar@linux.vnet.ibm.com, akpm@linux-foundation.org, jmorris@namei.org In-Reply-To: <1223302886.6774.32.camel@dyn536739.br.ibm.com> References: <20081003165738.GA28375@us.ibm.com> <1223061133.7639.23.camel@blackbox> <1223302886.6774.32.camel@dyn536739.br.ibm.com> Content-Type: text/plain Date: Mon, 06 Oct 2008 11:29:51 -0300 Message-Id: <1223303391.6774.39.camel@dyn536739.br.ibm.com> Mime-Version: 1.0 X-Mailer: Evolution 2.22.3.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4680 Lines: 173 This is a resubmission of rcu locking patch, posted some hours ago, addressing Serge Hallyn's comment. In the previous patch there was missing the spin_lock/unlock protecting list_add_rcu() in tpm_register_hardware(). There were also an unnecessary list_del() inside the same function, that is now being removed. Signed-off-by: Mimi Zohar Signed-off-by: Rajiv Andrade Acked-by: Serge E. Hallyn --- drivers/char/tpm/tpm.c | 61 +++++++++++++++++++----------------------------- 1 files changed, 24 insertions(+), 37 deletions(-) diff --git a/drivers/char/tpm/tpm.c b/drivers/char/tpm/tpm.c index dfd4e7f..e96ca5a 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 @@ -1230,21 +1218,20 @@ 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); put_device(chip->dev); + return NULL; } chip->bios_dir = tpm_bios_log_setup(devname); + /* Make chip available */ + spin_lock(&driver_lock); + list_add_rcu(&chip->list, &tpm_chip_list); + spin_unlock(&driver_lock); + return chip; } EXPORT_SYMBOL_GPL(tpm_register_hardware); -- 1.5.6.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/