[opensuse-kernel] [PATCH] efivars: Disable external interrupt while holding efivars->lock

From: Seiji Aguchi Git-commit: 81fa4e581d9283f7992a0d8c534bb141eb840a14 Patch-mainline: v3.9-rc1 References: bnc#808680 Target: openSUSE 12.3 [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 Acked-by: Mike Waychison Acked-by: Matt Fleming Signed-off-by: Tony Luck Acked-by: Lee, Chun-Yi --- drivers/firmware/efivars.c | 82 +++++++++++++++++++++++---------------------- 1 file changed, 42 insertions(+), 40 deletions(-) --- a/drivers/firmware/efivars.c +++ b/drivers/firmware/efivars.c @@ -405,10 +405,11 @@ 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", @@ -537,14 +538,14 @@ 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", @@ -713,7 +714,7 @@ static ssize_t efivarfs_file_write(struc * amounts of memory. Pick a default size of 64K if * QueryVariableInfo() isn't supported by the firmware. */ - spin_lock(&efivars->lock); + spin_lock_irq(&efivars->lock); if (!efivars->ops->query_variable_info) status = EFI_UNSUPPORTED; @@ -723,7 +724,7 @@ static ssize_t efivarfs_file_write(struc &remaining_size, &max_size); } - spin_unlock(&efivars->lock); + spin_unlock_irq(&efivars->lock); if (status != EFI_SUCCESS) { if (status != EFI_UNSUPPORTED) @@ -754,7 +755,7 @@ static ssize_t efivarfs_file_write(struc * set_variable call, and removal of the variable from the efivars * list (in the case of an authenticated delete). */ - spin_lock(&efivars->lock); + spin_lock_irq(&efivars->lock); status = efivars->ops->set_variable(var->var.VariableName, &var->var.VendorGuid, @@ -762,7 +763,7 @@ static ssize_t efivarfs_file_write(struc data); if (status != EFI_SUCCESS) { - spin_unlock(&efivars->lock); + spin_unlock_irq(&efivars->lock); kfree(data); return efi_status_to_err(status); @@ -783,21 +784,21 @@ static ssize_t efivarfs_file_write(struc NULL); if (status == EFI_BUFFER_TOO_SMALL) { - spin_unlock(&efivars->lock); + spin_unlock_irq(&efivars->lock); mutex_lock(&inode->i_mutex); i_size_write(inode, newdatasize + sizeof(attributes)); mutex_unlock(&inode->i_mutex); } else if (status == EFI_NOT_FOUND) { list_del(&var->list); - spin_unlock(&efivars->lock); + spin_unlock_irq(&efivars->lock); efivar_unregister(var); drop_nlink(inode); d_delete(file->f_dentry); dput(file->f_dentry); } else { - spin_unlock(&efivars->lock); + spin_unlock_irq(&efivars->lock); pr_warn("efivarfs: inconsistent EFI variable implementation? " "status = %lx\n", status); } @@ -819,11 +820,11 @@ static ssize_t efivarfs_file_read(struct void *data; ssize_t size = 0; - spin_lock(&efivars->lock); + spin_lock_irq(&efivars->lock); status = efivars->ops->get_variable(var->var.VariableName, &var->var.VendorGuid, &attributes, &datasize, NULL); - spin_unlock(&efivars->lock); + spin_unlock_irq(&efivars->lock); if (status != EFI_BUFFER_TOO_SMALL) return efi_status_to_err(status); @@ -833,12 +834,12 @@ static ssize_t efivarfs_file_read(struct if (!data) return -ENOMEM; - spin_lock(&efivars->lock); + spin_lock_irq(&efivars->lock); status = efivars->ops->get_variable(var->var.VariableName, &var->var.VendorGuid, &attributes, &datasize, (data + sizeof(attributes))); - spin_unlock(&efivars->lock); + spin_unlock_irq(&efivars->lock); if (status != EFI_SUCCESS) { size = efi_status_to_err(status); @@ -967,9 +968,9 @@ static int efivarfs_create(struct inode goto out; kobject_uevent(&var->kobj, KOBJ_ADD); - spin_lock(&efivars->lock); + spin_lock_irq(&efivars->lock); list_add(&var->list, &efivars->list); - spin_unlock(&efivars->lock); + spin_unlock_irq(&efivars->lock); d_instantiate(dentry, inode); dget(dentry); out: @@ -986,7 +987,7 @@ static int efivarfs_unlink(struct inode struct efivars *efivars = var->efivars; efi_status_t status; - spin_lock(&efivars->lock); + spin_lock_irq(&efivars->lock); status = efivars->ops->set_variable(var->var.VariableName, &var->var.VendorGuid, @@ -994,14 +995,14 @@ static int efivarfs_unlink(struct inode if (status == EFI_SUCCESS || status == EFI_NOT_FOUND) { list_del(&var->list); - spin_unlock(&efivars->lock); + spin_unlock_irq(&efivars->lock); efivar_unregister(var); drop_nlink(dentry->d_inode); dput(dentry); return 0; } - spin_unlock(&efivars->lock); + spin_unlock_irq(&efivars->lock); return -EINVAL; }; @@ -1146,13 +1147,13 @@ static int efivarfs_fill_super(struct su /* copied by the above to local storage in the dentry. */ kfree(name); - spin_lock(&efivars->lock); + spin_lock_irq(&efivars->lock); efivars->ops->get_variable(entry->var.VariableName, &entry->var.VendorGuid, &entry->var.Attributes, &size, NULL); - spin_unlock(&efivars->lock); + spin_unlock_irq(&efivars->lock); mutex_lock(&inode->i_mutex); inode->i_private = entry; @@ -1215,7 +1216,7 @@ 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; @@ -1225,7 +1226,7 @@ static int efi_pstore_close(struct pstor { struct efivars *efivars = psi->data; - spin_unlock(&efivars->lock); + spin_unlock_irq(&efivars->lock); return 0; } @@ -1281,6 +1282,7 @@ 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()); @@ -1291,10 +1293,10 @@ static int efi_pstore_write(enum pstore_ * this driver returns without entering firmware to avoid * hanging up. */ - if (!spin_trylock(&efivars->lock)) + if (!spin_trylock_irqsave(&efivars->lock, flags)) return -EBUSY; } else - spin_lock(&efivars->lock); + spin_lock_irqsave(&efivars->lock, flags); /* * Check if there is a space enough to log. @@ -1306,7 +1308,7 @@ 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; } @@ -1347,7 +1349,7 @@ 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); @@ -1431,7 +1433,7 @@ static ssize_t efivar_create(struct file return -EINVAL; } - spin_lock(&efivars->lock); + spin_lock_irq(&efivars->lock); /* * Does this variable already exist? @@ -1449,7 +1451,7 @@ static ssize_t efivar_create(struct file } } if (found) { - spin_unlock(&efivars->lock); + spin_unlock_irq(&efivars->lock); return -EINVAL; } @@ -1463,10 +1465,10 @@ 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, @@ -1494,7 +1496,7 @@ 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? @@ -1512,7 +1514,7 @@ 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 */ @@ -1528,12 +1530,12 @@ 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.... */ @@ -1648,9 +1650,9 @@ 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; } @@ -1719,9 +1721,9 @@ 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) -- To unsubscribe, e-mail: opensuse-kernel+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse-kernel+owner@opensuse.org