From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932764Ab2IDWHb (ORCPT ); Tue, 4 Sep 2012 18:07:31 -0400 Received: from usindpps06.hds.com ([207.126.252.19]:43741 "EHLO usindpps06.hds.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757729Ab2IDWH3 convert rfc822-to-8bit (ORCPT ); Tue, 4 Sep 2012 18:07:29 -0400 From: Seiji Aguchi To: Mike Waychison , "linux-kernel@vger.kernel.org" , "Luck, Tony (tony.luck@intel.com)" , "Matthew Garrett (mjg@redhat.com)" , "dzickus@redhat.com" , "linux-efi@vger.kernel.org" CC: "dle-develop@lists.sourceforge.net" , Satoru Moriya Subject: [RESEND][PATCH v4 1/3] efivars: Disable external interrupt while holding efivars->lock Thread-Topic: [RESEND][PATCH v4 1/3] efivars: Disable external interrupt while holding efivars->lock Thread-Index: Ac2K6Z1PkfwurN+BT0i6bGSVeNc7IA== Date: Tue, 4 Sep 2012 22:07:10 +0000 Message-ID: Accept-Language: ja-JP, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.74.43.113] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:5.7.7855,1.0.431,0.0.0000 definitions=2012-09-04_07:2012-09-04,2012-09-04,1970-01-01 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_policy_notspam policy=outbound_policy score=0 spamscore=0 ipscore=0 suspectscore=1 phishscore=0 bulkscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=6.0.2-1203120001 definitions=main-1209040247 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org efivars: Disable external interrupt while holding efivars->lock [Problem] Currently, efivars doesn't disable interrupt while taking efivars->lock. So, there is a risk to be deadlocking in a write callback of efi_pstore if kernel panics in interrupt context while taking efivars->lock. [Patch Description] This patch disables an external interruption while holding efivars->lock by replacing spin_lock/spin_unlock with spin_lock_irqsave/spin_unlock_irqrestore. As for spin_locks in open/close callbacks of efi_pstore, they moved to a read callback to pass a flags argument to spin_lock_irqsave/spin_unlock_irqrestore. Even if spin_locks in open/close callbacks are erased, a whole process of open/read/close is still serialized by psinfo->read_mutex which is taken in a pstore layer. Also, initialization of efivars->walk_entry moved to a read callback to protect list_first_entry() with efivars->lock. And some comments about efivars->walk_entry are added to avoid using it Signed-off-by: Seiji Aguchi --- drivers/firmware/efivars.c | 43 +++++++++++++++++++++++-------------------- 1 files changed, 23 insertions(+), 20 deletions(-) diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c index 47408e8..bd1df01 100644 --- a/drivers/firmware/efivars.c +++ b/drivers/firmware/efivars.c @@ -393,10 +393,11 @@ static efi_status_t get_var_data(struct efivars *efivars, struct efi_variable *var) { efi_status_t status; + unsigned long flags; - spin_lock(&efivars->lock); + spin_lock_irqsave(&efivars->lock, flags); status = get_var_data_locked(efivars, var); - spin_unlock(&efivars->lock); + spin_unlock_irqrestore(&efivars->lock, flags); if (status != EFI_SUCCESS) { printk(KERN_WARNING "efivars: get_variable() failed 0x%lx!\n", @@ -514,14 +515,14 @@ efivar_store_raw(struct efivar_entry *entry, const char *buf, size_t count) return -EINVAL; } - spin_lock(&efivars->lock); + spin_lock_irq(&efivars->lock); status = efivars->ops->set_variable(new_var->VariableName, &new_var->VendorGuid, new_var->Attributes, new_var->DataSize, new_var->Data); - spin_unlock(&efivars->lock); + spin_unlock_irq(&efivars->lock); if (status != EFI_SUCCESS) { printk(KERN_WARNING "efivars: set_variable() failed: status=%lx\n", @@ -632,7 +633,7 @@ static int efi_pstore_open(struct pstore_info *psi) { struct efivars *efivars = psi->data; - spin_lock(&efivars->lock); + spin_lock_irq(&efivars->lock); efivars->walk_entry = list_first_entry(&efivars->list, struct efivar_entry, list); return 0; @@ -642,7 +643,7 @@ static int efi_pstore_close(struct pstore_info *psi) { struct efivars *efivars = psi->data; - spin_unlock(&efivars->lock); + spin_unlock_irq(&efivars->lock); return 0; } @@ -696,11 +697,12 @@ static int efi_pstore_write(enum pstore_type_id type, struct efivars *efivars = psi->data; struct efivar_entry *entry, *found = NULL; int i, ret = 0; + unsigned long flags; sprintf(stub_name, "dump-type%u-%u-", type, part); sprintf(name, "%s%lu", stub_name, get_seconds()); - spin_lock(&efivars->lock); + spin_lock_irqsave(&efivars->lock, flags); for (i = 0; i < DUMP_NAME_LEN; i++) efi_name[i] = stub_name[i]; @@ -738,7 +740,7 @@ static int efi_pstore_write(enum pstore_type_id type, efivars->ops->set_variable(efi_name, &vendor, PSTORE_EFI_ATTRIBUTES, size, psi->buf); - spin_unlock(&efivars->lock); + spin_unlock_irqrestore(&efivars->lock, flags); if (found) efivar_unregister(found); @@ -822,7 +824,7 @@ static ssize_t efivar_create(struct file *filp, struct kobject *kobj, return -EINVAL; } - spin_lock(&efivars->lock); + spin_lock_irq(&efivars->lock); /* * Does this variable already exist? @@ -840,7 +842,7 @@ static ssize_t efivar_create(struct file *filp, struct kobject *kobj, } } if (found) { - spin_unlock(&efivars->lock); + spin_unlock_irq(&efivars->lock); return -EINVAL; } @@ -854,10 +856,10 @@ static ssize_t efivar_create(struct file *filp, struct kobject *kobj, if (status != EFI_SUCCESS) { printk(KERN_WARNING "efivars: set_variable() failed: status=%lx\n", status); - spin_unlock(&efivars->lock); + spin_unlock_irq(&efivars->lock); return -EIO; } - spin_unlock(&efivars->lock); + spin_unlock_irq(&efivars->lock); /* Create the entry in sysfs. Locking is not required here */ status = efivar_create_sysfs_entry(efivars, @@ -885,7 +887,7 @@ static ssize_t efivar_delete(struct file *filp, struct kobject *kobj, if (!capable(CAP_SYS_ADMIN)) return -EACCES; - spin_lock(&efivars->lock); + spin_lock_irq(&efivars->lock); /* * Does this variable already exist? @@ -903,7 +905,7 @@ static ssize_t efivar_delete(struct file *filp, struct kobject *kobj, } } if (!found) { - spin_unlock(&efivars->lock); + spin_unlock_irq(&efivars->lock); return -EINVAL; } /* force the Attributes/DataSize to 0 to ensure deletion */ @@ -919,12 +921,12 @@ static ssize_t efivar_delete(struct file *filp, struct kobject *kobj, if (status != EFI_SUCCESS) { printk(KERN_WARNING "efivars: set_variable() failed: status=%lx\n", status); - spin_unlock(&efivars->lock); + spin_unlock_irq(&efivars->lock); return -EIO; } list_del(&search_efivar->list); /* We need to release this lock before unregistering. */ - spin_unlock(&efivars->lock); + spin_unlock_irq(&efivars->lock); efivar_unregister(search_efivar); /* It's dead Jim.... */ @@ -993,6 +995,7 @@ efivar_create_sysfs_entry(struct efivars *efivars, int i, short_name_size = variable_name_size / sizeof(efi_char16_t) + 38; char *short_name; struct efivar_entry *new_efivar; + unsigned long flags; short_name = kzalloc(short_name_size + 1, GFP_KERNEL); new_efivar = kzalloc(sizeof(struct efivar_entry), GFP_KERNEL); @@ -1032,9 +1035,9 @@ efivar_create_sysfs_entry(struct efivars *efivars, kfree(short_name); short_name = NULL; - spin_lock(&efivars->lock); + spin_lock_irqsave(&efivars->lock, flags); list_add(&new_efivar->list, &efivars->list); - spin_unlock(&efivars->lock); + spin_unlock_irqrestore(&efivars->lock, flags); return 0; } @@ -1103,9 +1106,9 @@ void unregister_efivars(struct efivars *efivars) struct efivar_entry *entry, *n; list_for_each_entry_safe(entry, n, &efivars->list, list) { - spin_lock(&efivars->lock); + spin_lock_irq(&efivars->lock); list_del(&entry->list); - spin_unlock(&efivars->lock); + spin_unlock_irq(&efivars->lock); efivar_unregister(entry); } if (efivars->new_var) -- 1.7.1