From a93bc0c6e07ed9bac44700280e65e2945d864fd4 Mon Sep 17 00:00:00 2001 From: Seiji Aguchi Date: Tue, 12 Feb 2013 13:04:41 -0800 Subject: efi_pstore: Introducing workqueue updating sysfs [Problem] efi_pstore creates sysfs entries, which enable users to access to NVRAM, in a write callback. If a kernel panic happens in an interrupt context, it may fail because it could sleep due to dynamic memory allocations during creating sysfs entries. [Patch Description] This patch removes sysfs operations from a write callback by introducing a workqueue updating sysfs entries which is scheduled after the write callback is called. Also, the workqueue is kicked in a just oops case. A system will go down in other cases such as panic, clean shutdown and emergency restart. And we don't need to create sysfs entries because there is no chance for users to access to them. efi_pstore will be robust against a kernel panic in an interrupt context with this patch. Signed-off-by: Seiji Aguchi Acked-by: Matt Fleming Signed-off-by: Tony Luck --- include/linux/efi.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'include/linux/efi.h') diff --git a/include/linux/efi.h b/include/linux/efi.h index 8b84916dc671..d0c68aee0925 100644 --- a/include/linux/efi.h +++ b/include/linux/efi.h @@ -728,7 +728,8 @@ struct efivars { * 1) ->list - adds, removals, reads, writes * 2) ops.[gs]et_variable() calls. * It must not be held when creating sysfs entries or calling kmalloc. - * ops.get_next_variable() is only called from register_efivars(), + * ops.get_next_variable() is only called from register_efivars() + * or efivar_update_sysfs_entries(), * which is protected by the BKL, so that path is safe. */ spinlock_t lock; -- cgit v1.2.3