This is a note to let you know that I've just added the patch titled
[media] dib8000: make 32 bits read atomic
to the 3.12-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:
dib8000-make-32-bits-read-atomic.patch
and it can be found in the queue-3.12 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 5ac64ba12aca3bef18e61c866583155a3bbf81c4 Mon Sep 17 00:00:00 2001
From: Mauro Carvalho Chehab <m.chehab@xxxxxxxxxxx>
Date: Fri, 13 Dec 2013 10:35:03 -0300
Subject: [media] dib8000: make 32 bits read atomic
From: Mauro Carvalho Chehab <m.chehab@xxxxxxxxxxx>
commit 5ac64ba12aca3bef18e61c866583155a3bbf81c4 upstream.
As the dvb-frontend kthread can be called anytime, it can race
with some get status ioctl. So, it seems better to avoid one to
race with the other while reading a 32 bits register.
I can't see any other reason for having a mutex there at I2C, except
to provide such kind of protection, as the I2C core already has a
mutex to protect I2C transfers.
Note: instead of this approach, it could eventually remove the dib8000
specific mutex for it, and either group the 4 ops into one xfer or
to manually control the I2C mutex. The main advantage of the current
approach is that the changes are smaller and more puntual.
Signed-off-by: Mauro Carvalho Chehab <m.chehab@xxxxxxxxxxx>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@xxxxxxxxxxx>
Acked-by: Patrick Boettcher <pboettcher@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/media/dvb-frontends/dib8000.c | 33 +++++++++++++++++++++++++--------
1 file changed, 25 insertions(+), 8 deletions(-)
--- a/drivers/media/dvb-frontends/dib8000.c
+++ b/drivers/media/dvb-frontends/dib8000.c
@@ -157,15 +157,10 @@ static u16 dib8000_i2c_read16(struct i2c
return ret;
}
-static u16 dib8000_read_word(struct dib8000_state *state, u16 reg)
+static u16 __dib8000_read_word(struct dib8000_state *state, u16 reg)
{
u16 ret;
- if (mutex_lock_interruptible(&state->i2c_buffer_lock) < 0) {
- dprintk("could not acquire lock");
- return 0;
- }
-
state->i2c_write_buffer[0] = reg >> 8;
state->i2c_write_buffer[1] = reg & 0xff;
@@ -183,6 +178,21 @@ static u16 dib8000_read_word(struct dib8
dprintk("i2c read error on %d", reg);
ret = (state->i2c_read_buffer[0] << 8) | state->i2c_read_buffer[1];
+
+ return ret;
+}
+
+static u16 dib8000_read_word(struct dib8000_state *state, u16 reg)
+{
+ u16 ret;
+
+ if (mutex_lock_interruptible(&state->i2c_buffer_lock) < 0) {
+ dprintk("could not acquire lock");
+ return 0;
+ }
+
+ ret = __dib8000_read_word(state, reg);
+
mutex_unlock(&state->i2c_buffer_lock);
return ret;
@@ -192,8 +202,15 @@ static u32 dib8000_read32(struct dib8000
{
u16 rw[2];
- rw[0] = dib8000_read_word(state, reg + 0);
- rw[1] = dib8000_read_word(state, reg + 1);
+ if (mutex_lock_interruptible(&state->i2c_buffer_lock) < 0) {
+ dprintk("could not acquire lock");
+ return 0;
+ }
+
+ rw[0] = __dib8000_read_word(state, reg + 0);
+ rw[1] = __dib8000_read_word(state, reg + 1);
+
+ mutex_unlock(&state->i2c_buffer_lock);
return ((rw[0] << 16) | (rw[1]));
}
Patches currently in stable-queue which might be from m.chehab@xxxxxxxxxxx are
queue-3.12/it913x-add-support-for-avermedia-h335-id-0x0335.patch
queue-3.12/m88rs2000-set-symbol-rate-accurately.patch
queue-3.12/media-anysee-fix-non-working-e30-combo-plus-dvb-t.patch
queue-3.12/media-media-v4l2-dev-fix-video-device-index-assignment.patch
queue-3.12/dib8000-fix-regression-with-dib807x.patch
queue-3.12/media-s5p_mfc-remove-s5p_mfc_get_node_type-function.patch
queue-3.12/dib8000-make-32-bits-read-atomic.patch
queue-3.12/m88rs2000-add-m88rs2000_set_carrieroffset.patch
queue-3.12/nxt200x-increase-write-buffer-size.patch
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