[PATCH] fix timerfd support

[PATCH] fix timerfd support

[Feng Li]

From: vonnyfly <lifeng1519@gmail.com>

There are some exceptions when checking features in Makefile.
In my debian, timerfd.h path is not '/usr/include/sys/timerfd.h'.

 $ find /usr/include -name "timerfd.h" | head -n1
 /usr/include/x86_64-linux-gnu/sys/timerfd.h

In my raspberrypi, the path is also not here.

So, it will not enable timerfd, even though it supports actually.
When I enable it after fix.  I have seen error logs.
"Failed to write to pipe".

From the code, we could know in add_work, it calls work_timer_schedule_evt.
work_timer_schedule_evt will call write(timer_fd[1], ...), then it will print error log,
because timer_fd[1] == -1.

When enable timerfd support, makefile check incorrectly.
work_timer_schedule_evt should check support of timerfd.

Signed-off-by: vonnyfly <lifeng1519@gmail.com>
---
 usr/Makefile | 2 +-
 usr/work.c   | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/usr/Makefile b/usr/Makefile
index 1fae7e7..d4e3eaf 100644
--- a/usr/Makefile
+++ b/usr/Makefile
@@ -5,7 +5,7 @@ ifneq ($(shell test -e /usr/include/linux/signalfd.h && echo 1),)
 CFLAGS += -DUSE_SIGNALFD
 endif
 
-ifneq ($(shell test -e /usr/include/sys/timerfd.h && echo 1),)
+ifneq ($(shell test -n $(shell find /usr/include -name "timerfd.h" | head -n1) && echo 1),)
 CFLAGS += -DUSE_TIMERFD
 endif
 
diff --git a/usr/work.c b/usr/work.c
index 6b9ec12..d760c22 100644
--- a/usr/work.c
+++ b/usr/work.c
@@ -59,7 +59,7 @@ static void work_timer_schedule_evt(void)
 	unsigned int n = 0;
 	int err;
 
-	if (timer_pending)
+	if (timer_pending || timer_fd[1] < 0)
 		return;
 
 	timer_pending = 1;
-- 
2.8.1

Re: [PATCH] fix timerfd support

[FUJITA Tomonori]

On Tue,  3 May 2016 16:45:38 +0800
Feng Li <li.feng@oracle.com> wrote:

> From: vonnyfly <lifeng1519@gmail.com>
> 
> There are some exceptions when checking features in Makefile.
> In my debian, timerfd.h path is not '/usr/include/sys/timerfd.h'.
> 
>  $ find /usr/include -name "timerfd.h" | head -n1
>  /usr/include/x86_64-linux-gnu/sys/timerfd.h
> 
> In my raspberrypi, the path is also not here.
> 
> So, it will not enable timerfd, even though it supports actually.
> When I enable it after fix.  I have seen error logs.
> "Failed to write to pipe".
> 
> From the code, we could know in add_work, it calls work_timer_schedule_evt.
> work_timer_schedule_evt will call write(timer_fd[1], ...), then it will print error log,
> because timer_fd[1] == -1.

Looks like with timerfd enabled, work_timer_schedule_evt() isn't
called. add_work() is always called with the non-zero second
argument. How you hit the above bug?

> When enable timerfd support, makefile check incorrectly.
> work_timer_schedule_evt should check support of timerfd.
> 
> Signed-off-by: vonnyfly <lifeng1519@gmail.com>
> ---
>  usr/Makefile | 2 +-
>  usr/work.c   | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)

Applied, thanks.

Re: [PATCH] fix timerfd support

[Alex Feng]

Hi Tomonori ,

Thanks for your response.
Please see my response inline.

On 2016/5/10 7:35, FUJITA Tomonori wrote:
> On Tue,  3 May 2016 16:45:38 +0800
> Feng Li <li.feng@oracle.com> wrote:
>
>> From: vonnyfly <lifeng1519@gmail.com>
>>
>> There are some exceptions when checking features in Makefile.
>> In my debian, timerfd.h path is not '/usr/include/sys/timerfd.h'.
>>
>>   $ find /usr/include -name "timerfd.h" | head -n1
>>   /usr/include/x86_64-linux-gnu/sys/timerfd.h
>>
>> In my raspberrypi, the path is also not here.
>>
>> So, it will not enable timerfd, even though it supports actually.
>> When I enable it after fix.  I have seen error logs.
>> "Failed to write to pipe".
>>
>>  From the code, we could know in add_work, it calls work_timer_schedule_evt.
>> work_timer_schedule_evt will call write(timer_fd[1], ...), then it will print error log,
>> because timer_fd[1] == -1.
> Looks like with timerfd enabled, work_timer_schedule_evt() isn't
> called. add_work() is always called with the non-zero second
> argument. How you hit the above bug?
The easiest way to see this log is to replace 'add_work(&nop_work, 1);' 
to 'add_work(&nop_work, 0);'.
Like this:

--- a/usr/iscsi/iscsi_tcp.c
+++ b/usr/iscsi/iscsi_tcp.c
@@ -438,7 +438,7 @@ static int iscsi_tcp_init(void)

         nop_work.func = iscsi_tcp_nop_work_handler;
         nop_work.data = &nop_work;
-       add_work(&nop_work, 1);
+       add_work(&nop_work, 0);

tgtd: work_timer_schedule_evt(69) Failed to write to pipe, Bad file 
descriptor

>
>> When enable timerfd support, makefile check incorrectly.
>> work_timer_schedule_evt should check support of timerfd.
>>
>> Signed-off-by: vonnyfly <lifeng1519@gmail.com>
>> ---
>>   usr/Makefile | 2 +-
>>   usr/work.c   | 2 +-
>>   2 files changed, 2 insertions(+), 2 deletions(-)
> Applied, thanks.