af_unix: Cache state->msg in unix_stream_read_generic().

af_unix: Cache state->msg in unix_stream_read_generic().

[ Upstream commit 8b77338eb2af74bb93986e4a8cfd86724168fe39 ]

In unix_stream_read_generic(), state->msg is fetched multiple times.

Let's cache it in a local variable.

Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20250702223606.1054680-6-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Stable-dep-of: 7bf3a476ce43 ("af_unix: Read sk_peek_offset() again after sleeping in unix_stream_read_generic().")
Signed-off-by: Sasha Levin <sashal@kernel.org>