From 796f8d9b98fc92a5e9aaea8cf932957850332f51 Mon Sep 17 00:00:00 2001 From: David Gibson Date: Mon, 7 Nov 2005 00:59:33 -0800 Subject: [PATCH] [PATCH] FUTEX_WAKE_OP: enhanced error handling The code for FUTEX_WAKE_OP calls an arch callback, futex_atomic_op_inuser(). That callback can return an error code, but currently the caller assumes any error is EFAULT, and will try various things to resolve the fault before eventually giving up with EFAULT (regardless of the original error code). This is not a theoretical case - arch callbacks currently return -ENOSYS if the opcode they are given is bogus. This patch alters the code to detect non-EFAULT errors and return them directly to the user. Of course, whether -ENOSYS is the correct return value for the bogus opcode case, or whether EINVAL would be more appropriate is another question. Signed-off-by: David Gibson Cc: Rusty Russell Cc: Ingo Molnar Cc: Jamie Lokier Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/futex.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/kernel/futex.c b/kernel/futex.c index 3b4d5ad44cc6..aca8d10704f6 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -365,6 +365,11 @@ retry: if (bh1 != bh2) spin_unlock(&bh2->lock); + if (unlikely(op_ret != -EFAULT)) { + ret = op_ret; + goto out; + } + /* futex_atomic_op_inuser needs to both read and write * *(int __user *)uaddr2, but we can't modify it * non-atomically. Therefore, if get_user below is not -- 2.20.1