Patch "ALSA: emu10k1: don't deadlock in proc-functions" has been added to the 4.0-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    ALSA: emu10k1: don't deadlock in proc-functions

to the 4.0-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     alsa-emu10k1-don-t-deadlock-in-proc-functions.patch
and it can be found in the queue-4.0 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 91bf0c2dcb935a87e5c0795f5047456b965fd143 Mon Sep 17 00:00:00 2001
From: Michael Gernoth <michael@gernoth.net>
Date: Thu, 9 Apr 2015 23:42:15 +0200
Subject: ALSA: emu10k1: don't deadlock in proc-functions

From: Michael Gernoth <michael@gernoth.net>

commit 91bf0c2dcb935a87e5c0795f5047456b965fd143 upstream.

The functions snd_emu10k1_proc_spdif_read and snd_emu1010_fpga_read
acquire the emu_lock before accessing the FPGA. The function used
to access the FPGA (snd_emu1010_fpga_read) also tries to take
the emu_lock which causes a deadlock.
Remove the outer locking in the proc-functions (guarding only the
already safe fpga read) to prevent this deadlock.

[removed superfluous flags variables too -- tiwai]

Signed-off-by: Michael Gernoth <michael@gernoth.net>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 sound/pci/emu10k1/emuproc.c |   12 ------------
 1 file changed, 12 deletions(-)

--- a/sound/pci/emu10k1/emuproc.c
+++ b/sound/pci/emu10k1/emuproc.c
@@ -241,31 +241,22 @@ static void snd_emu10k1_proc_spdif_read(
 	struct snd_emu10k1 *emu = entry->private_data;
 	u32 value;
 	u32 value2;
-	unsigned long flags;
 	u32 rate;
 
 	if (emu->card_capabilities->emu_model) {
-		spin_lock_irqsave(&emu->emu_lock, flags);
 		snd_emu1010_fpga_read(emu, 0x38, &value);
-		spin_unlock_irqrestore(&emu->emu_lock, flags);
 		if ((value & 0x1) == 0) {
-			spin_lock_irqsave(&emu->emu_lock, flags);
 			snd_emu1010_fpga_read(emu, 0x2a, &value);
 			snd_emu1010_fpga_read(emu, 0x2b, &value2);
-			spin_unlock_irqrestore(&emu->emu_lock, flags);
 			rate = 0x1770000 / (((value << 5) | value2)+1);	
 			snd_iprintf(buffer, "ADAT Locked : %u\n", rate);
 		} else {
 			snd_iprintf(buffer, "ADAT Unlocked\n");
 		}
-		spin_lock_irqsave(&emu->emu_lock, flags);
 		snd_emu1010_fpga_read(emu, 0x20, &value);
-		spin_unlock_irqrestore(&emu->emu_lock, flags);
 		if ((value & 0x4) == 0) {
-			spin_lock_irqsave(&emu->emu_lock, flags);
 			snd_emu1010_fpga_read(emu, 0x28, &value);
 			snd_emu1010_fpga_read(emu, 0x29, &value2);
-			spin_unlock_irqrestore(&emu->emu_lock, flags);
 			rate = 0x1770000 / (((value << 5) | value2)+1);	
 			snd_iprintf(buffer, "SPDIF Locked : %d\n", rate);
 		} else {
@@ -410,14 +401,11 @@ static void snd_emu_proc_emu1010_reg_rea
 {
 	struct snd_emu10k1 *emu = entry->private_data;
 	u32 value;
-	unsigned long flags;
 	int i;
 	snd_iprintf(buffer, "EMU1010 Registers:\n\n");
 
 	for(i = 0; i < 0x40; i+=1) {
-		spin_lock_irqsave(&emu->emu_lock, flags);
 		snd_emu1010_fpga_read(emu, i, &value);
-		spin_unlock_irqrestore(&emu->emu_lock, flags);
 		snd_iprintf(buffer, "%02X: %08X, %02X\n", i, value, (value >> 8) & 0x7f);
 	}
 }


Patches currently in stable-queue which might be from michael@gernoth.net are

queue-4.0/alsa-emu10k1-don-t-deadlock-in-proc-functions.patch