[PATCH] makedumpfile: Fix a bug when multi-threads feature meets enospace

[Masahiko Hayashi]

Hi  Zhou-san

I will forward Tachibana's mail.

Thank you

>-----Original Message-----
>From: Hayashi Masahiko(林 正彦)
>Sent: Friday, February 09, 2018 8:24 PM
>To: Zhou Wenjian <zhouwj.fi at gmail.com>
>Cc: kexec at lists.infradead.org
>Subject: FW: [PATCH] makedumpfile: Fix a bug when multi-threads feature meets enospace
>
>>-----Original Message-----
>>From: Tachibana Masaki(橘 正樹)
>>Sent: Friday, February 09, 2018 8:05 PM
>>To: Zhou Wenjian <zhouwj.fi at gmail.com>
>>Cc: kexec at lists.infradead.org; Hayashi Masahiko(林 正彦) <mas-hayashi at tg.jp.nec.com>
>>Subject: RE: [PATCH] makedumpfile: Fix a bug when multi-threads feature meets enospace
>>
>>Hi Zhou,
>>
>>Sorry for the late reply.
>>Makedumpfile team are busy now for another development.
>>I'll reply in about a week.
>>
>>Thanks
>>tachibana
>>
>>> -----Original Message-----
>>> From: kexec [mailto:kexec-bounces at lists.infradead.org] On Behalf Of Zhou Wenjian
>>> Sent: Thursday, February 08, 2018 8:53 PM
>>> To: kexec at lists.infradead.org
>>> Cc: Kumagai Atsushi <ats-kumagai at wm.jp.nec.com>; Suzuki Keiichirou <kei-suzuki at xr.jp.nec.com>
>>> Subject: Re: [PATCH] makedumpfile: Fix a bug when multi-threads feature meets enospace
>>>
>>> ping...
>>>
>>>
>>> On 01/29/2018 08:54 PM, Zhou Wenjian wrote:
>>> > Currently, when multi-threads feature meets enospace error,
>>> > the main thread will call pthread_join(). However, there is one
>>> > thread doing while{} and won't stop.
>>> >
>>> >                  pthread_mutex_lock(&info->page_data_mutex);
>>> >                  while (page_data_buf[index].used != FALSE) {
>>> >                          index = (index + 1) % info->num_buffers;
>>> >                  }
>>> >                  page_data_buf[index].used = TRUE;
>>> >                  pthread_mutex_unlock(&info->page_data_mutex);
>>> >
>>> > Then makedumpfile hangs.
>>> >
>>> > This patch add a cancel point in while{}.
>>> >
>>> > Signed-off-by: Zhou Wenjian <zhouwj.fi at gmail.com>
>>> > ---
>>> >   makedumpfile.c | 4 +++-
>>> >   1 file changed, 3 insertions(+), 1 deletion(-)
>>> >
>>> > diff --git a/makedumpfile.c b/makedumpfile.c
>>> > index ed138d3..f7ad50c 100644
>>> > --- a/makedumpfile.c
>>> > +++ b/makedumpfile.c
>>> > @@ -7731,11 +7731,13 @@ kdump_thread_function_cyclic(void *arg) {
>>> >   		buf_ready = FALSE;
>>> >
>>> >   		pthread_mutex_lock(&info->page_data_mutex);
>>> > +		pthread_cleanup_push(pthread_mutex_unlock, &info->page_data_mutex);
>>> >   		while (page_data_buf[index].used != FALSE) {
>>> > +			pthread_testcancel();
>>> >   			index = (index + 1) % info->num_buffers;
>>> >   		}
>>> >   		page_data_buf[index].used = TRUE;
>>> > -		pthread_mutex_unlock(&info->page_data_mutex);
>>> > +		pthread_cleanup_pop(1);
>>> >
>>> >   		while (buf_ready == FALSE) {
>>> >   			pthread_testcancel();
>>>
>>> --
>>> Thanks
>>> Zhou
>>>
>>>
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