linux-kernel - [PATCH 5.9 190/252] ALSA: firewire: Clean up a locking issue in copy_resp_to

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Date:   Mon, 23 Nov 2020 13:22:20 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Dan Carpenter <dan.carpenter@...cle.com>,
        Takashi Sakamoto <o-takashi@...amocchi.jp>,
        Takashi Iwai <tiwai@...e.de>
Subject: [PATCH 5.9 190/252] ALSA: firewire: Clean up a locking issue in copy_resp_to_buf()

From: Dan Carpenter <dan.carpenter@...cle.com>

commit 02a9c6ee4183af2e438454c55098b828a96085fb upstream.

The spin_lock/unlock_irq() functions cannot be nested.  The problem is
that presumably we would want the IRQs to be re-enabled on the second
call the spin_unlock_irq() but instead it will be enabled at the first
call so IRQs will be enabled earlier than expected.

In this situation the copy_resp_to_buf() function is only called from
one function and it is called with IRQs disabled.  We can just use
the regular spin_lock/unlock() functions.

Fixes: 555e8a8f7f14 ("ALSA: fireworks: Add command/response functionality into hwdep interface")
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
Acked-by: Takashi Sakamoto <o-takashi@...amocchi.jp>
Cc: <stable@...r.kernel.org>
Link: https://lore.kernel.org/r/20201113101241.GB168908@mwanda
Signed-off-by: Takashi Iwai <tiwai@...e.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 sound/firewire/fireworks/fireworks_transaction.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/sound/firewire/fireworks/fireworks_transaction.c
+++ b/sound/firewire/fireworks/fireworks_transaction.c
@@ -123,7 +123,7 @@ copy_resp_to_buf(struct snd_efw *efw, vo
 	t = (struct snd_efw_transaction *)data;
 	length = min_t(size_t, be32_to_cpu(t->length) * sizeof(u32), length);
 
-	spin_lock_irq(&efw->lock);
+	spin_lock(&efw->lock);
 
 	if (efw->push_ptr < efw->pull_ptr)
 		capacity = (unsigned int)(efw->pull_ptr - efw->push_ptr);
@@ -190,7 +190,7 @@ handle_resp_for_user(struct fw_card *car
 
 	copy_resp_to_buf(efw, data, length, rcode);
 end:
-	spin_unlock_irq(&instances_lock);
+	spin_unlock(&instances_lock);
 }
 
 static void