[PATCH 3.12 039/142] ALSA: emu10k1: don't deadlock in proc-functions

Jiri Slaby
2015-05-16T08:06:52Z

From: Michael Gernoth <michael@gernoth.net>

3.12-stable review patch. If anyone has any objections, please let me know.

===============

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: Jiri Slaby <jslaby@suse.cz>
---
sound/pci/emu10k1/emuproc.c | 12 ------------
1 file changed, 12 deletions(-)

diff --git a/sound/pci/emu10k1/emuproc.c b/sound/pci/emu10k1/emuproc.c
index 2ca9f2e93139..53745f4c2bf5 100644
--- 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_info_entry *entry,
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_read(struct snd_info_entry *entry,
{
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);
}
}
--
2.3.7