From b1b8afb83336b66ac7198111aad4ead41132b53f Mon Sep 17 00:00:00 2001
From: Jack Morgenstein <jackm@dev.mellanox.co.il>
Date: Sat, 5 Sep 2009 20:24:24 -0700
Subject: [PATCH] IB/uverbs: Return ENOSYS for unimplemented commands (not
 EINVAL)

Since the original commit 883a99c7 ("[IB] uverbs: Add a mask of device
methods allowed for userspace"), the uverbs core returns EINVAL for
commands not implemented by a specific low-level driver.

This creates a problem that there is no way to tell the difference
between an unimplemented command and an implemented one which is
incorrectly invoked (which also returns EINVAL).

The fix is to have unimplemented commands return ENOSYS.

Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
---
 drivers/infiniband/core/uverbs_main.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/infiniband/core/uverbs_main.c b/drivers/infiniband/core/uverbs_main.c
index 1a3ac3d882b8..d3fff9e008a3 100644
--- a/drivers/infiniband/core/uverbs_main.c
+++ b/drivers/infiniband/core/uverbs_main.c
@@ -584,14 +584,16 @@ static ssize_t ib_uverbs_write(struct file *filp, const char __user *buf,
 
 	if (hdr.command < 0				||
 	    hdr.command >= ARRAY_SIZE(uverbs_cmd_table) ||
-	    !uverbs_cmd_table[hdr.command]		||
-	    !(file->device->ib_dev->uverbs_cmd_mask & (1ull << hdr.command)))
+	    !uverbs_cmd_table[hdr.command])
 		return -EINVAL;
 
 	if (!file->ucontext &&
 	    hdr.command != IB_USER_VERBS_CMD_GET_CONTEXT)
 		return -EINVAL;
 
+	if (!(file->device->ib_dev->uverbs_cmd_mask & (1ull << hdr.command)))
+		return -ENOSYS;
+
 	return uverbs_cmd_table[hdr.command](file, buf + sizeof hdr,
 					     hdr.in_words * 4, hdr.out_words * 4);
 }