From 81fa4e581d9283f7992a0d8c534bb141eb840a14 Mon Sep 17 00:00:00 2001 From: Seiji Aguchi Date: Tue, 12 Feb 2013 12:59:07 -0800 Subject: efivars: Disable external interrupt while holding efivars->lock [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 --- drivers/firmware/efivars.c | 86 ++++++++++++++++++++++++---------------------- 1 file changed, 44 insertions(+), 42 deletions(-) (limited to 'drivers/firmware') diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c index ef5070d86f88..a64fb7bda365 100644 --- 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 *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", @@ -713,7 +714,7 @@ static ssize_t efivarfs_file_write(struct file *file, * 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(struct file *file, &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(struct file *file, * 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(struct file *file, data); if (status != EFI_SUCCESS) { - spin_unlock(&efivars->lock); + spin_unlock_irq(&efivars->lock); kfree(data); return efi_status_to_err(status); @@ -783,20 +784,20 @@ static ssize_t efivarfs_file_write(struct file *file, 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); 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); } @@ -818,11 +819,11 @@ static ssize_t efivarfs_file_read(struct file *file, char __user *userbuf, 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); @@ -832,12 +833,12 @@ static ssize_t efivarfs_file_read(struct file *file, char __user *userbuf, 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); @@ -965,9 +966,9 @@ static int efivarfs_create(struct inode *dir, struct dentry *dentry, 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: @@ -984,7 +985,7 @@ static int efivarfs_unlink(struct inode *dir, struct dentry *dentry) 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, @@ -992,14 +993,14 @@ static int efivarfs_unlink(struct inode *dir, struct dentry *dentry) 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(dir); dput(dentry); return 0; } - spin_unlock(&efivars->lock); + spin_unlock_irq(&efivars->lock); return -EINVAL; }; @@ -1065,13 +1066,13 @@ static int efivarfs_fill_super(struct super_block *sb, void *data, int silent) /* 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; @@ -1122,7 +1123,7 @@ 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; @@ -1132,7 +1133,7 @@ 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; } @@ -1208,6 +1209,7 @@ static int efi_pstore_write(enum pstore_type_id type, int i, ret = 0; u64 storage_space, remaining_space, max_variable_size; efi_status_t status = EFI_NOT_FOUND; + unsigned long flags; if (pstore_cannot_block_path(reason)) { /* @@ -1215,10 +1217,10 @@ static int efi_pstore_write(enum pstore_type_id type, * 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. @@ -1230,7 +1232,7 @@ static int efi_pstore_write(enum pstore_type_id type, &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; } @@ -1244,7 +1246,7 @@ 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 (size) ret = efivar_create_sysfs_entry(efivars, @@ -1271,7 +1273,7 @@ static int efi_pstore_erase(enum pstore_type_id type, u64 id, int count, sprintf(name, "dump-type%u-%u-%d-%lu", type, (unsigned int)id, count, time.tv_sec); - spin_lock(&efivars->lock); + spin_lock_irq(&efivars->lock); for (i = 0; i < DUMP_NAME_LEN; i++) efi_name[i] = name[i]; @@ -1315,7 +1317,7 @@ static int efi_pstore_erase(enum pstore_type_id type, u64 id, int count, if (found) list_del(&found->list); - spin_unlock(&efivars->lock); + spin_unlock_irq(&efivars->lock); if (found) efivar_unregister(found); @@ -1385,7 +1387,7 @@ 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? @@ -1403,7 +1405,7 @@ static ssize_t efivar_create(struct file *filp, struct kobject *kobj, } } if (found) { - spin_unlock(&efivars->lock); + spin_unlock_irq(&efivars->lock); return -EINVAL; } @@ -1417,10 +1419,10 @@ 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, @@ -1448,7 +1450,7 @@ 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? @@ -1466,7 +1468,7 @@ 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 */ @@ -1482,12 +1484,12 @@ 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.... */ @@ -1602,9 +1604,9 @@ efivar_create_sysfs_entry(struct efivars *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; } @@ -1673,9 +1675,9 @@ 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) -- cgit v1.2.1