efi: Don't use spinlocks for efi vars
All efivars operations are protected by a spinlock which prevents
interruptions and preemption. This is too restricted, we just need a
lock preventing concurrency.
The idea is to use a semaphore of count 1 and to have two ways of
locking, depending on the context:
- In interrupt context, we call down_trylock(), if it fails we return
an error
- In normal context, we call down_interruptible()
We don't use a mutex here because the mutex_trylock() function must not
be called from interrupt context, whereas the down_trylock() can.
Signed-off-by: Sylvain Chouleur <sylvain.chouleur@intel.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Leif Lindholm <leif.lindholm@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Sylvain Chouleur <sylvain.chouleur@gmail.com>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
diff --git a/fs/efivarfs/inode.c b/fs/efivarfs/inode.c
index 1d73fc6..cbb50ca 100644
--- a/fs/efivarfs/inode.c
+++ b/fs/efivarfs/inode.c
@@ -105,7 +105,10 @@
inode->i_private = var;
- efivar_entry_add(var, &efivarfs_list);
+ err = efivar_entry_add(var, &efivarfs_list);
+ if (err)
+ goto out;
+
d_instantiate(dentry, inode);
dget(dentry);
out: