On Mon, 2013-03-11 at 17:47 -0400, Josh Boyer wrote:
> Upstream commit 81fa4e581d9283f7992a0d8c534bb141eb840a14
[...]
This version didn't apply to 3.2.y, but the bug does seem to affect it.
And efivars is essentially the same in 3.2.y and 3.4.y. Does this
backport look right for them?
Ben.
---
Date: Mon, 11 Mar 2013 17:47:42 -0400
From: Josh Boyer <jwboyer@xxxxxxxxxx>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Subject: efivars: Disable external interrupt while holding efivars->lock
Content-Transfer-Encoding: 8bit
commit 81fa4e581d9283f7992a0d8c534bb141eb840a14 upstream.
[Problem]
There is a scenario which efi_pstore fails to log messages in a panic case.
- CPUA holds an efi_var->lock in either efivarfs parts
or efi_pstore with interrupt enabled.
- CPUB panics and sends IPI to CPUA in smp_send_stop().
- CPUA stops with holding the lock.
- CPUB kicks efi_pstore_write() via kmsg_dump(KSMG_DUMP_PANIC)
but it returns without logging messages.
[Patch Description]
This patch disables an external interruption while holding efivars->lock
as follows.
In efi_pstore_write() and get_var_data(), spin_lock/spin_unlock is
replaced by spin_lock_irqsave/spin_unlock_irqrestore because they may
be called in an interrupt context.
In other functions, they are replaced by spin_lock_irq/spin_unlock_irq.
because they are all called from a process context.
By applying this patch, we can avoid the problem above with
a following senario.
- CPUA holds an efi_var->lock with interrupt disabled.
- CPUB panics and sends IPI to CPUA in smp_send_stop().
- CPUA receives the IPI after releasing the lock because it is
disabling interrupt while holding the lock.
- CPUB waits for one sec until CPUA releases the lock.
- CPUB kicks efi_pstore_write() via kmsg_dump(KSMG_DUMP_PANIC)
And it can hold the lock successfully.
Signed-off-by: Seiji Aguchi <seiji.aguchi@xxxxxxx>
Acked-by: Mike Waychison <mikew@xxxxxxxxxx>
Acked-by: Matt Fleming <matt.fleming@xxxxxxxxx>
Signed-off-by: Tony Luck <tony.luck@xxxxxxxxx>
[bwh: Backported to 3.2:
- Drop efivarfs changes
- Adjust context
- Drop change to efi_pstore_erase(), which is implemented using
efi_pstore_write() here]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
drivers/firmware/efivars.c | 84 ++++++++++++++++++++++++----------------------
1 file changed, 43 insertions(+), 41 deletions(-)
--- 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",
@@ -525,14 +526,14 @@ efivar_store_raw(struct efivar_entry *en
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",
@@ -643,7 +644,7 @@ static int efi_pstore_open(struct pstore
{
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;
@@ -653,7 +654,7 @@ static int efi_pstore_close(struct pstor
{
struct efivars *efivars = psi->data;
- spin_unlock(&efivars->lock);
+ spin_unlock_irq(&efivars->lock);
return 0;
}
@@ -708,11 +709,12 @@ static int efi_pstore_write(enum pstore_
int i, ret = 0;
u64 storage_space, remaining_space, max_variable_size;
efi_status_t status = EFI_NOT_FOUND;
+ 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);
/*
* Check if there is a space enough to log.
@@ -724,7 +726,7 @@ static int efi_pstore_write(enum pstore_
&remaining_space,
&max_variable_size);
if (status || remaining_space < size + DUMP_NAME_LEN * 2) {
- spin_unlock(&efivars->lock);
+ spin_unlock_irqrestore(&efivars->lock, flags);
*id = part;
return -ENOSPC;
}
@@ -765,7 +767,7 @@ static int efi_pstore_write(enum pstore_
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);
@@ -848,7 +850,7 @@ static ssize_t efivar_create(struct file
return -EINVAL;
}
- spin_lock(&efivars->lock);
+ spin_lock_irq(&efivars->lock);
/*
* Does this variable already exist?
@@ -866,7 +868,7 @@ static ssize_t efivar_create(struct file
}
}
if (found) {
- spin_unlock(&efivars->lock);
+ spin_unlock_irq(&efivars->lock);
return -EINVAL;
}
@@ -880,10 +882,10 @@ static ssize_t efivar_create(struct file
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,
@@ -911,7 +913,7 @@ static ssize_t efivar_delete(struct file
if (!capable(CAP_SYS_ADMIN))
return -EACCES;
- spin_lock(&efivars->lock);
+ spin_lock_irq(&efivars->lock);
/*
* Does this variable already exist?
@@ -929,7 +931,7 @@ static ssize_t efivar_delete(struct file
}
}
if (!found) {
- spin_unlock(&efivars->lock);
+ spin_unlock_irq(&efivars->lock);
return -EINVAL;
}
/* force the Attributes/DataSize to 0 to ensure deletion */
@@ -945,12 +947,12 @@ static ssize_t efivar_delete(struct file
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.... */
@@ -1058,9 +1060,9 @@ efivar_create_sysfs_entry(struct efivars
kfree(short_name);
short_name = NULL;
- spin_lock(&efivars->lock);
+ spin_lock_irq(&efivars->lock);
list_add(&new_efivar->list, &efivars->list);
- spin_unlock(&efivars->lock);
+ spin_unlock_irq(&efivars->lock);
return 0;
}
@@ -1129,9 +1131,9 @@ void unregister_efivars(struct 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)
--
Ben Hutchings
Usenet is essentially a HUGE group of people passing notes in class.
- Rachel Kadel, `A Quick Guide to Newsgroup Etiquette'
Attachment:
signature.asc
Description: This is a digitally signed message part