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Patch "ALSA: emu10k1: don't deadlock in proc-functions" has been added to the 3.10-stable tree

PATCH [email protected] 1 participant 1 message May 2, 2015

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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 3.10-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-3.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From 91bf0c2dcb935a87e5c0795f5047456b965fd143 Mon Sep 17 00:00:00 2001

From: Michael Gernoth <[email protected]>
Date: Thu, 9 Apr 2015 23:42:15 +0200
Subject: ALSA: emu10k1: don't deadlock in proc-functions

From: Michael Gernoth <[email protected]>

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 <[email protected]>
Signed-off-by Takashi Iwai <[email protected]>
Signed-off-by Greg Kroah-Hartman <[email protected]>
---
 sound/pci/emu10k1/emuproc.c |   12 ------------
 1 file changed, 12 deletions(-)
sound/pci/emu10k1/emuproc.c +0 -12
@@ -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 [email protected] are

queue-3.10/alsa-emu10k1-don-t-deadlock-in-proc-functions.patch