* [PATCH] Input: serio_raw - ensure we don't block in non-blocking read
@ 2012-04-03 20:24 Dmitry Torokhov
2012-04-11 7:23 ` Dmitry Torokhov
2012-04-17 8:56 ` Che-liang Chiou
0 siblings, 2 replies; 5+ messages in thread
From: Dmitry Torokhov @ 2012-04-03 20:24 UTC (permalink / raw)
To: linux-input; +Cc: Wanlong Gao, Che-Liang Chiou, David Herrmann, linux-kernel
Avoid calling wait_event_interruptible() if client requested non-blocking
read, since it is not guaranteed that another thread will not consume
event after we checked if serio_raw->head != serio_raw->tail.
Also ensure we do not return 0 but keep waiting instead in blocking case,
when another thread steals "our" byte.
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
---
drivers/input/serio/serio_raw.c | 43 ++++++++++++++++++++++----------------
1 files changed, 25 insertions(+), 18 deletions(-)
diff --git a/drivers/input/serio/serio_raw.c b/drivers/input/serio/serio_raw.c
index 4494233..094d6fb 100644
--- a/drivers/input/serio/serio_raw.c
+++ b/drivers/input/serio/serio_raw.c
@@ -165,31 +165,38 @@ static ssize_t serio_raw_read(struct file *file, char __user *buffer,
struct serio_raw *serio_raw = client->serio_raw;
char uninitialized_var(c);
ssize_t read = 0;
- int retval;
+ int error = 0;
- if (serio_raw->dead)
- return -ENODEV;
+ do {
+ if (serio_raw->dead)
+ return -ENODEV;
- if (serio_raw->head == serio_raw->tail && (file->f_flags & O_NONBLOCK))
- return -EAGAIN;
+ if (serio_raw->head == serio_raw->tail &&
+ (file->f_flags & O_NONBLOCK))
+ return -EAGAIN;
- retval = wait_event_interruptible(serio_raw->wait,
- serio_raw->head != serio_raw->tail || serio_raw->dead);
- if (retval)
- return retval;
+ if (count == 0)
+ break;
- if (serio_raw->dead)
- return -ENODEV;
+ while (read < count && serio_raw_fetch_byte(serio_raw, &c)) {
+ if (put_user(c, buffer++)) {
+ error = -EFAULT;
+ goto out;
+ }
+ read++;
+ }
- while (read < count && serio_raw_fetch_byte(serio_raw, &c)) {
- if (put_user(c, buffer++)) {
- retval = -EFAULT;
+ if (read)
break;
- }
- read++;
- }
- return read ?: retval;
+ if (!(file->f_flags & O_NONBLOCK))
+ error = wait_event_interruptible(serio_raw->wait,
+ serio_raw->head != serio_raw->tail ||
+ serio_raw->dead);
+ } while (!error);
+
+out:
+ return read ?: error;
}
static ssize_t serio_raw_write(struct file *file, const char __user *buffer,
--
1.7.7.6
--
Dmitry
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH] Input: serio_raw - ensure we don't block in non-blocking read
2012-04-03 20:24 [PATCH] Input: serio_raw - ensure we don't block in non-blocking read Dmitry Torokhov
@ 2012-04-11 7:23 ` Dmitry Torokhov
2012-04-13 16:50 ` David Herrmann
2012-04-17 8:56 ` Che-liang Chiou
1 sibling, 1 reply; 5+ messages in thread
From: Dmitry Torokhov @ 2012-04-11 7:23 UTC (permalink / raw)
To: linux-input; +Cc: Wanlong Gao, Che-Liang Chiou, David Herrmann, linux-kernel
On Tue, Apr 03, 2012 at 01:24:33PM -0700, Dmitry Torokhov wrote:
> Avoid calling wait_event_interruptible() if client requested non-blocking
> read, since it is not guaranteed that another thread will not consume
> event after we checked if serio_raw->head != serio_raw->tail.
>
> Also ensure we do not return 0 but keep waiting instead in blocking case,
> when another thread steals "our" byte.
>
> Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
Anyone? It would be nice if someone could review my patches as well,
otherwise we may end up with breakages...
Thanks.
> ---
> drivers/input/serio/serio_raw.c | 43 ++++++++++++++++++++++----------------
> 1 files changed, 25 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/input/serio/serio_raw.c b/drivers/input/serio/serio_raw.c
> index 4494233..094d6fb 100644
> --- a/drivers/input/serio/serio_raw.c
> +++ b/drivers/input/serio/serio_raw.c
> @@ -165,31 +165,38 @@ static ssize_t serio_raw_read(struct file *file, char __user *buffer,
> struct serio_raw *serio_raw = client->serio_raw;
> char uninitialized_var(c);
> ssize_t read = 0;
> - int retval;
> + int error = 0;
>
> - if (serio_raw->dead)
> - return -ENODEV;
> + do {
> + if (serio_raw->dead)
> + return -ENODEV;
>
> - if (serio_raw->head == serio_raw->tail && (file->f_flags & O_NONBLOCK))
> - return -EAGAIN;
> + if (serio_raw->head == serio_raw->tail &&
> + (file->f_flags & O_NONBLOCK))
> + return -EAGAIN;
>
> - retval = wait_event_interruptible(serio_raw->wait,
> - serio_raw->head != serio_raw->tail || serio_raw->dead);
> - if (retval)
> - return retval;
> + if (count == 0)
> + break;
>
> - if (serio_raw->dead)
> - return -ENODEV;
> + while (read < count && serio_raw_fetch_byte(serio_raw, &c)) {
> + if (put_user(c, buffer++)) {
> + error = -EFAULT;
> + goto out;
> + }
> + read++;
> + }
>
> - while (read < count && serio_raw_fetch_byte(serio_raw, &c)) {
> - if (put_user(c, buffer++)) {
> - retval = -EFAULT;
> + if (read)
> break;
> - }
> - read++;
> - }
>
> - return read ?: retval;
> + if (!(file->f_flags & O_NONBLOCK))
> + error = wait_event_interruptible(serio_raw->wait,
> + serio_raw->head != serio_raw->tail ||
> + serio_raw->dead);
> + } while (!error);
> +
> +out:
> + return read ?: error;
> }
>
> static ssize_t serio_raw_write(struct file *file, const char __user *buffer,
> --
> 1.7.7.6
>
--
Dmitry
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] Input: serio_raw - ensure we don't block in non-blocking read
2012-04-11 7:23 ` Dmitry Torokhov
@ 2012-04-13 16:50 ` David Herrmann
0 siblings, 0 replies; 5+ messages in thread
From: David Herrmann @ 2012-04-13 16:50 UTC (permalink / raw)
To: Dmitry Torokhov; +Cc: linux-input, Wanlong Gao, Che-Liang Chiou, linux-kernel
Hi Dmitry
On Wed, Apr 11, 2012 at 9:23 AM, Dmitry Torokhov
<dmitry.torokhov@gmail.com> wrote:
> On Tue, Apr 03, 2012 at 01:24:33PM -0700, Dmitry Torokhov wrote:
>> Avoid calling wait_event_interruptible() if client requested non-blocking
>> read, since it is not guaranteed that another thread will not consume
>> event after we checked if serio_raw->head != serio_raw->tail.
>>
>> Also ensure we do not return 0 but keep waiting instead in blocking case,
>> when another thread steals "our" byte.
>>
>> Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
>
> Anyone? It would be nice if someone could review my patches as well,
> otherwise we may end up with breakages...
I cannot test the driver as I don't have the devices, but I reviewed
it and it looks fine.
> Thanks.
Regards
David
>> ---
>> drivers/input/serio/serio_raw.c | 43 ++++++++++++++++++++++----------------
>> 1 files changed, 25 insertions(+), 18 deletions(-)
>>
>> diff --git a/drivers/input/serio/serio_raw.c b/drivers/input/serio/serio_raw.c
>> index 4494233..094d6fb 100644
>> --- a/drivers/input/serio/serio_raw.c
>> +++ b/drivers/input/serio/serio_raw.c
>> @@ -165,31 +165,38 @@ static ssize_t serio_raw_read(struct file *file, char __user *buffer,
>> struct serio_raw *serio_raw = client->serio_raw;
>> char uninitialized_var(c);
>> ssize_t read = 0;
>> - int retval;
>> + int error = 0;
>>
>> - if (serio_raw->dead)
>> - return -ENODEV;
>> + do {
>> + if (serio_raw->dead)
>> + return -ENODEV;
>>
>> - if (serio_raw->head == serio_raw->tail && (file->f_flags & O_NONBLOCK))
>> - return -EAGAIN;
>> + if (serio_raw->head == serio_raw->tail &&
>> + (file->f_flags & O_NONBLOCK))
>> + return -EAGAIN;
>>
>> - retval = wait_event_interruptible(serio_raw->wait,
>> - serio_raw->head != serio_raw->tail || serio_raw->dead);
>> - if (retval)
>> - return retval;
>> + if (count == 0)
>> + break;
>>
>> - if (serio_raw->dead)
>> - return -ENODEV;
>> + while (read < count && serio_raw_fetch_byte(serio_raw, &c)) {
>> + if (put_user(c, buffer++)) {
>> + error = -EFAULT;
>> + goto out;
>> + }
>> + read++;
>> + }
>>
>> - while (read < count && serio_raw_fetch_byte(serio_raw, &c)) {
>> - if (put_user(c, buffer++)) {
>> - retval = -EFAULT;
>> + if (read)
>> break;
>> - }
>> - read++;
>> - }
>>
>> - return read ?: retval;
>> + if (!(file->f_flags & O_NONBLOCK))
>> + error = wait_event_interruptible(serio_raw->wait,
>> + serio_raw->head != serio_raw->tail ||
>> + serio_raw->dead);
>> + } while (!error);
>> +
>> +out:
>> + return read ?: error;
>> }
>>
>> static ssize_t serio_raw_write(struct file *file, const char __user *buffer,
>> --
>> 1.7.7.6
>>
>
> --
> Dmitry
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] Input: serio_raw - ensure we don't block in non-blocking read
2012-04-03 20:24 [PATCH] Input: serio_raw - ensure we don't block in non-blocking read Dmitry Torokhov
2012-04-11 7:23 ` Dmitry Torokhov
@ 2012-04-17 8:56 ` Che-liang Chiou
2012-04-17 9:14 ` Che-liang Chiou
1 sibling, 1 reply; 5+ messages in thread
From: Che-liang Chiou @ 2012-04-17 8:56 UTC (permalink / raw)
To: Dmitry Torokhov; +Cc: linux-input, Wanlong Gao, David Herrmann, linux-kernel
[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain; charset=UTF-8, Size: 3482 bytes --]
I didn't test the patch, but the logic looks fine to me.
On Wed, Apr 4, 2012 at 4:24 AM, Dmitry Torokhov
<dmitry.torokhov@gmail.com> wrote:
> Avoid calling wait_event_interruptible() if client requested non-blocking
> read, since it is not guaranteed that another thread will not consume
> event after we checked if serio_raw->head != serio_raw->tail.
>
> Also ensure we do not return 0 but keep waiting instead in blocking case,
> when another thread steals "our" byte.
>
> Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
> ---
> Â drivers/input/serio/serio_raw.c | Â 43 ++++++++++++++++++++++----------------
> Â 1 files changed, 25 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/input/serio/serio_raw.c b/drivers/input/serio/serio_raw.c
> index 4494233..094d6fb 100644
> --- a/drivers/input/serio/serio_raw.c
> +++ b/drivers/input/serio/serio_raw.c
> @@ -165,31 +165,38 @@ static ssize_t serio_raw_read(struct file *file, char __user *buffer,
> Â Â Â Â struct serio_raw *serio_raw = client->serio_raw;
> Â Â Â Â char uninitialized_var(c);
> Â Â Â Â ssize_t read = 0;
> - Â Â Â int retval;
> + Â Â Â int error = 0;
>
> - Â Â Â if (serio_raw->dead)
> - Â Â Â Â Â Â Â return -ENODEV;
> + Â Â Â do {
> + Â Â Â Â Â Â Â if (serio_raw->dead)
> + Â Â Â Â Â Â Â Â Â Â Â return -ENODEV;
>
> - Â Â Â if (serio_raw->head == serio_raw->tail && (file->f_flags & O_NONBLOCK))
> - Â Â Â Â Â Â Â return -EAGAIN;
> + Â Â Â Â Â Â Â if (serio_raw->head == serio_raw->tail &&
> + Â Â Â Â Â Â Â Â Â (file->f_flags & O_NONBLOCK))
> + Â Â Â Â Â Â Â Â Â Â Â return -EAGAIN;
>
> - Â Â Â retval = wait_event_interruptible(serio_raw->wait,
> - Â Â Â Â Â Â Â Â Â Â Â serio_raw->head != serio_raw->tail || serio_raw->dead);
> - Â Â Â if (retval)
> - Â Â Â Â Â Â Â return retval;
> + Â Â Â Â Â Â Â if (count == 0)
> + Â Â Â Â Â Â Â Â Â Â Â break;
>
> - Â Â Â if (serio_raw->dead)
> - Â Â Â Â Â Â Â return -ENODEV;
> + Â Â Â Â Â Â Â while (read < count && serio_raw_fetch_byte(serio_raw, &c)) {
> + Â Â Â Â Â Â Â Â Â Â Â if (put_user(c, buffer++)) {
> + Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â error = -EFAULT;
> + Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â goto out;
> + Â Â Â Â Â Â Â Â Â Â Â }
> + Â Â Â Â Â Â Â Â Â Â Â read++;
> + Â Â Â Â Â Â Â }
>
> - Â Â Â while (read < count && serio_raw_fetch_byte(serio_raw, &c)) {
> - Â Â Â Â Â Â Â if (put_user(c, buffer++)) {
> - Â Â Â Â Â Â Â Â Â Â Â retval = -EFAULT;
> + Â Â Â Â Â Â Â if (read)
> Â Â Â Â Â Â Â Â Â Â Â Â break;
> - Â Â Â Â Â Â Â }
> - Â Â Â Â Â Â Â read++;
> - Â Â Â }
>
> - Â Â Â return read ?: retval;
> + Â Â Â Â Â Â Â if (!(file->f_flags & O_NONBLOCK))
> + Â Â Â Â Â Â Â Â Â Â Â error = wait_event_interruptible(serio_raw->wait,
> + Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â serio_raw->head != serio_raw->tail ||
> + Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â serio_raw->dead);
> + Â Â Â } while (!error);
> +
> +out:
> + Â Â Â return read ?: error;
> Â }
>
> Â static ssize_t serio_raw_write(struct file *file, const char __user *buffer,
> --
> 1.7.7.6
>
>
> --
> Dmitry
ÿôèº{.nÇ+‰·Ÿ®‰†+%ŠËÿ±éݶ\x17¥Šwÿº{.nÇ+‰·¥Š{±þG«éÿŠ{ayº\x1dʇڙë,j\a¢f£¢·hšïêÿ‘êçz_è®\x03(階ŠÝ¢j"ú\x1a¶^[m§ÿÿ¾\a«þG«éÿ¢¸?™¨èÚ&£ø§~á¶iO•æ¬z·švØ^\x14\x04\x1a¶^[m§ÿÿÃ\fÿ¶ìÿ¢¸?–I¥
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] Input: serio_raw - ensure we don't block in non-blocking read
2012-04-17 8:56 ` Che-liang Chiou
@ 2012-04-17 9:14 ` Che-liang Chiou
0 siblings, 0 replies; 5+ messages in thread
From: Che-liang Chiou @ 2012-04-17 9:14 UTC (permalink / raw)
To: Dmitry Torokhov; +Cc: linux-input, Wanlong Gao, David Herrmann, linux-kernel
[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain; charset=UTF-8, Size: 3700 bytes --]
Reviewed-by: Che-Liang Chiou <clchiou@chromium.org>
On Tue, Apr 17, 2012 at 4:56 PM, Che-liang Chiou <clchiou@chromium.org> wrote:
> I didn't test the patch, but the logic looks fine to me.
>
> On Wed, Apr 4, 2012 at 4:24 AM, Dmitry Torokhov
> <dmitry.torokhov@gmail.com> wrote:
>> Avoid calling wait_event_interruptible() if client requested non-blocking
>> read, since it is not guaranteed that another thread will not consume
>> event after we checked if serio_raw->head != serio_raw->tail.
>>
>> Also ensure we do not return 0 but keep waiting instead in blocking case,
>> when another thread steals "our" byte.
>>
>> Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
>> ---
>> Â drivers/input/serio/serio_raw.c | Â 43 ++++++++++++++++++++++----------------
>> Â 1 files changed, 25 insertions(+), 18 deletions(-)
>>
>> diff --git a/drivers/input/serio/serio_raw.c b/drivers/input/serio/serio_raw.c
>> index 4494233..094d6fb 100644
>> --- a/drivers/input/serio/serio_raw.c
>> +++ b/drivers/input/serio/serio_raw.c
>> @@ -165,31 +165,38 @@ static ssize_t serio_raw_read(struct file *file, char __user *buffer,
>> Â Â Â Â struct serio_raw *serio_raw = client->serio_raw;
>> Â Â Â Â char uninitialized_var(c);
>> Â Â Â Â ssize_t read = 0;
>> - Â Â Â int retval;
>> + Â Â Â int error = 0;
>>
>> - Â Â Â if (serio_raw->dead)
>> - Â Â Â Â Â Â Â return -ENODEV;
>> + Â Â Â do {
>> + Â Â Â Â Â Â Â if (serio_raw->dead)
>> + Â Â Â Â Â Â Â Â Â Â Â return -ENODEV;
>>
>> - Â Â Â if (serio_raw->head == serio_raw->tail && (file->f_flags & O_NONBLOCK))
>> - Â Â Â Â Â Â Â return -EAGAIN;
>> + Â Â Â Â Â Â Â if (serio_raw->head == serio_raw->tail &&
>> + Â Â Â Â Â Â Â Â Â (file->f_flags & O_NONBLOCK))
>> + Â Â Â Â Â Â Â Â Â Â Â return -EAGAIN;
>>
>> - Â Â Â retval = wait_event_interruptible(serio_raw->wait,
>> - Â Â Â Â Â Â Â Â Â Â Â serio_raw->head != serio_raw->tail || serio_raw->dead);
>> - Â Â Â if (retval)
>> - Â Â Â Â Â Â Â return retval;
>> + Â Â Â Â Â Â Â if (count == 0)
>> + Â Â Â Â Â Â Â Â Â Â Â break;
>>
>> - Â Â Â if (serio_raw->dead)
>> - Â Â Â Â Â Â Â return -ENODEV;
>> + Â Â Â Â Â Â Â while (read < count && serio_raw_fetch_byte(serio_raw, &c)) {
>> + Â Â Â Â Â Â Â Â Â Â Â if (put_user(c, buffer++)) {
>> + Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â error = -EFAULT;
>> + Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â goto out;
>> + Â Â Â Â Â Â Â Â Â Â Â }
>> + Â Â Â Â Â Â Â Â Â Â Â read++;
>> + Â Â Â Â Â Â Â }
>>
>> - Â Â Â while (read < count && serio_raw_fetch_byte(serio_raw, &c)) {
>> - Â Â Â Â Â Â Â if (put_user(c, buffer++)) {
>> - Â Â Â Â Â Â Â Â Â Â Â retval = -EFAULT;
>> + Â Â Â Â Â Â Â if (read)
>> Â Â Â Â Â Â Â Â Â Â Â Â break;
>> - Â Â Â Â Â Â Â }
>> - Â Â Â Â Â Â Â read++;
>> - Â Â Â }
>>
>> - Â Â Â return read ?: retval;
>> + Â Â Â Â Â Â Â if (!(file->f_flags & O_NONBLOCK))
>> + Â Â Â Â Â Â Â Â Â Â Â error = wait_event_interruptible(serio_raw->wait,
>> + Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â serio_raw->head != serio_raw->tail ||
>> + Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â serio_raw->dead);
>> + Â Â Â } while (!error);
>> +
>> +out:
>> + Â Â Â return read ?: error;
>> Â }
>>
>> Â static ssize_t serio_raw_write(struct file *file, const char __user *buffer,
>> --
>> 1.7.7.6
>>
>>
>> --
>> Dmitry
ÿôèº{.nÇ+‰·Ÿ®‰†+%ŠËÿ±éݶ\x17¥Šwÿº{.nÇ+‰·¥Š{±þG«éÿŠ{ayº\x1dʇڙë,j\a¢f£¢·hšïêÿ‘êçz_è®\x03(階ŠÝ¢j"ú\x1a¶^[m§ÿÿ¾\a«þG«éÿ¢¸?™¨èÚ&£ø§~á¶iO•æ¬z·švØ^\x14\x04\x1a¶^[m§ÿÿÃ\fÿ¶ìÿ¢¸?–I¥
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2012-04-17 9:15 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2012-04-03 20:24 [PATCH] Input: serio_raw - ensure we don't block in non-blocking read Dmitry Torokhov
2012-04-11 7:23 ` Dmitry Torokhov
2012-04-13 16:50 ` David Herrmann
2012-04-17 8:56 ` Che-liang Chiou
2012-04-17 9:14 ` Che-liang Chiou
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).