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>

diff --git a/drivers/infiniband/core/uverbs_main.c b/drivers/infiniband/core/uverbs_main.c
index 1a3ac3d882b8897f80076fbf16bd7a80b88623f9..d3fff9e008a3e01f1f81795101738ae236b02dcb 100644 (file)
--- 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);
 }