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Date: Tue, 21 Aug 2012 20:35:43 +0000
From: Seiji Aguchi <seiji.aguchi@....com>
To: Mike Waychison <mikew@...gle.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"Luck, Tony (tony.luck@...el.com)" <tony.luck@...el.com>,
"Matthew Garrett (mjg@...hat.com)" <mjg@...hat.com>,
"dzickus@...hat.com" <dzickus@...hat.com>
CC: "dle-develop@...ts.sourceforge.net"
<dle-develop@...ts.sourceforge.net>,
Satoru Moriya <satoru.moriya@....com>
Subject: [RFC][PATCH v4 1/3] 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 as follows
- In efi_pstore_open()/efi_pstore_close(), replace spin_lock/spin_unlock with spin_lock_irq/spin_unlock_irq
because they are called in a process context when users access to /dev/pstore.
- In unregister_efivars(), replace them with spin_lock_irq/spin_unlock_irq
because they are called in a process context when unloading this module.
- Also, in efivar_create()/efivar_store_raw()/efivar_delete(), replace them with spin_lock_irq/spin_unlock_irq
because they are called in a process context when users access to /sys/firmware/efi/vars/{new_var|del_var}.
- In other function calls, replace spin_lock/spin_unlock with spin_lock_irqsave/spin_unlock_irqrestore.
Signed-off-by: Seiji Aguchi <seiji.aguchi@....com>
---
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
--
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