[dpdk-dev] [PATCH] eal_interrupts.c: properly init struct epoll_event (valgrind)

[dpdk-dev] [PATCH] eal_interrupts.c: properly init struct epoll_event (valgrind)

[Matthew Hall]

Signed-off-by: Matthew Hall <mhall@mhcomputing.net>
---
 lib/librte_eal/linuxapp/eal/eal_interrupts.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/lib/librte_eal/linuxapp/eal/eal_interrupts.c b/lib/librte_eal/linuxapp/eal/eal_interrupts.c
index 06b26a9..b33ccdb 100644
--- a/lib/librte_eal/linuxapp/eal/eal_interrupts.c
+++ b/lib/librte_eal/linuxapp/eal/eal_interrupts.c
@@ -800,6 +800,7 @@ static __attribute__((noreturn)) void *
 eal_intr_thread_main(__rte_unused void *arg)
 {
 	struct epoll_event ev;
+	memset(&ev, 0, sizeof(ev));
 
 	/* host thread, never break out */
 	for (;;) {
-- 
2.5.0

Re: [dpdk-dev] [PATCH] eal_interrupts.c: properly init struct epoll_event (valgrind)

[Stephen Hemminger]

On Fri, 12 Feb 2016 22:41:18 -0800
Matthew Hall <mhall@mhcomputing.net> wrote:

> Signed-off-by: Matthew Hall <mhall@mhcomputing.net>
> ---
>  lib/librte_eal/linuxapp/eal/eal_interrupts.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/lib/librte_eal/linuxapp/eal/eal_interrupts.c b/lib/librte_eal/linuxapp/eal/eal_interrupts.c
> index 06b26a9..b33ccdb 100644
> --- a/lib/librte_eal/linuxapp/eal/eal_interrupts.c
> +++ b/lib/librte_eal/linuxapp/eal/eal_interrupts.c
> @@ -800,6 +800,7 @@ static __attribute__((noreturn)) void *
>  eal_intr_thread_main(__rte_unused void *arg)
>  {
>  	struct epoll_event ev;
> +	memset(&ev, 0, sizeof(ev));
>  
>  	/* host thread, never break out */
>  	for (;;) {

I wonder why valgrind is giving this false report.
The only place this data structure is used is here, and all fields
in epoll_event are correctly set.

		TAILQ_FOREACH(src, &intr_sources, next) {
			if (src->callbacks.tqh_first == NULL)
				continue; /* skip those with no callbacks */
			ev.events = EPOLLIN | EPOLLPRI;
			ev.data.fd = src->intr_handle.fd;

			/**
			 * add all the uio device file descriptor
			 * into wait list.
			 */
			if (epoll_ctl(pfd, EPOLL_CTL_ADD,
					src->intr_handle.fd, &ev) < 0){
				rte_panic("Error adding fd %d epoll_ctl, %s\n",
					src->intr_handle.fd, strerror(errno));

A better patch would be to move the data structure into the
code block used, and get rid of the useless else (rte_panic never returns);
and fix the indentation, and use C99 initialization which should make valgrind
happier.

The moral is don't just slap memsets around

diff --git a/lib/librte_eal/linuxapp/eal/eal_interrupts.c b/lib/librte_eal/linuxapp/eal/eal_interrupts.c
index 06b26a9..d53826e 100644
--- a/lib/librte_eal/linuxapp/eal/eal_interrupts.c
+++ b/lib/librte_eal/linuxapp/eal/eal_interrupts.c
@@ -799,8 +799,6 @@ eal_intr_handle_interrupts(int pfd, unsigned totalfds)
 static __attribute__((noreturn)) void *
 eal_intr_thread_main(__rte_unused void *arg)
 {
-	struct epoll_event ev;
-
 	/* host thread, never break out */
 	for (;;) {
 		/* build up the epoll fd with all descriptors we are to
@@ -834,20 +832,22 @@ eal_intr_thread_main(__rte_unused void *arg)
 		TAILQ_FOREACH(src, &intr_sources, next) {
 			if (src->callbacks.tqh_first == NULL)
 				continue; /* skip those with no callbacks */
-			ev.events = EPOLLIN | EPOLLPRI;
-			ev.data.fd = src->intr_handle.fd;
+
+			struct epoll_event ev = {
+				.events = EPOLLIN | EPOLLPRI,
+				.data.fd = src->intr_handle.fd,
+			};
 
 			/**
 			 * add all the uio device file descriptor
 			 * into wait list.
 			 */
 			if (epoll_ctl(pfd, EPOLL_CTL_ADD,
-					src->intr_handle.fd, &ev) < 0){
+					src->intr_handle.fd, &ev) < 0)
 				rte_panic("Error adding fd %d epoll_ctl, %s\n",
 					src->intr_handle.fd, strerror(errno));
-			}
-			else
-				numfds++;
+
+			numfds++;
 		}
 		rte_spinlock_unlock(&intr_lock);
 		/* serve the interrupt */

Re: [dpdk-dev] [PATCH] eal_interrupts.c: properly init struct epoll_event (valgrind)

[Thomas Monjalon]

Hi Stephen,

Please, could you turn it into a real patch with your sign-off?
Thanks

2016-02-14 12:22, Stephen Hemminger:
> A better patch would be to move the data structure into the
> code block used, and get rid of the useless else (rte_panic never returns);
> and fix the indentation, and use C99 initialization which should make valgrind
> happier.
> 
> The moral is don't just slap memsets around
> 
> diff --git a/lib/librte_eal/linuxapp/eal/eal_interrupts.c b/lib/librte_eal/linuxapp/eal/eal_interrupts.c
> index 06b26a9..d53826e 100644
> --- a/lib/librte_eal/linuxapp/eal/eal_interrupts.c
> +++ b/lib/librte_eal/linuxapp/eal/eal_interrupts.c
> @@ -799,8 +799,6 @@ eal_intr_handle_interrupts(int pfd, unsigned totalfds)
>  static __attribute__((noreturn)) void *
>  eal_intr_thread_main(__rte_unused void *arg)
>  {
> -	struct epoll_event ev;
> -
>  	/* host thread, never break out */
>  	for (;;) {
>  		/* build up the epoll fd with all descriptors we are to
> @@ -834,20 +832,22 @@ eal_intr_thread_main(__rte_unused void *arg)
>  		TAILQ_FOREACH(src, &intr_sources, next) {
>  			if (src->callbacks.tqh_first == NULL)
>  				continue; /* skip those with no callbacks */
> -			ev.events = EPOLLIN | EPOLLPRI;
> -			ev.data.fd = src->intr_handle.fd;
> +
> +			struct epoll_event ev = {
> +				.events = EPOLLIN | EPOLLPRI,
> +				.data.fd = src->intr_handle.fd,
> +			};
>  
>  			/**
>  			 * add all the uio device file descriptor
>  			 * into wait list.
>  			 */
>  			if (epoll_ctl(pfd, EPOLL_CTL_ADD,
> -					src->intr_handle.fd, &ev) < 0){
> +					src->intr_handle.fd, &ev) < 0)
>  				rte_panic("Error adding fd %d epoll_ctl, %s\n",
>  					src->intr_handle.fd, strerror(errno));
> -			}
> -			else
> -				numfds++;
> +
> +			numfds++;
>  		}
>  		rte_spinlock_unlock(&intr_lock);
>  		/* serve the interrupt */

Re: [dpdk-dev] [PATCH] eal_interrupts.c: properly init struct epoll_event (valgrind)

[Stephen Hemminger]

On Thu, 17 Mar 2016 15:18:15 +0100
Thomas Monjalon <thomas.monjalon@6wind.com> wrote:

> Hi Stephen,
> 
> Please, could you turn it into a real patch with your sign-off?
> Thanks
> 
> 2016-02-14 12:22, Stephen Hemminger:
> > A better patch would be to move the data structure into the
> > code block used, and get rid of the useless else (rte_panic never returns);
> > and fix the indentation, and use C99 initialization which should make valgrind
> > happier.
> > 
> > The moral is don't just slap memsets around
> > 
> > diff --git a/lib/librte_eal/linuxapp/eal/eal_interrupts.c b/lib/librte_eal/linuxapp/eal/eal_interrupts.c
> > index 06b26a9..d53826e 100644
> > --- a/lib/librte_eal/linuxapp/eal/eal_interrupts.c
> > +++ b/lib/librte_eal/linuxapp/eal/eal_interrupts.c
> > @@ -799,8 +799,6 @@ eal_intr_handle_interrupts(int pfd, unsigned totalfds)
> >  static __attribute__((noreturn)) void *
> >  eal_intr_thread_main(__rte_unused void *arg)
> >  {
> > -	struct epoll_event ev;
> > -
> >  	/* host thread, never break out */
> >  	for (;;) {
> >  		/* build up the epoll fd with all descriptors we are to
> > @@ -834,20 +832,22 @@ eal_intr_thread_main(__rte_unused void *arg)
> >  		TAILQ_FOREACH(src, &intr_sources, next) {
> >  			if (src->callbacks.tqh_first == NULL)
> >  				continue; /* skip those with no callbacks */
> > -			ev.events = EPOLLIN | EPOLLPRI;
> > -			ev.data.fd = src->intr_handle.fd;
> > +
> > +			struct epoll_event ev = {
> > +				.events = EPOLLIN | EPOLLPRI,
> > +				.data.fd = src->intr_handle.fd,
> > +			};
> >  
> >  			/**
> >  			 * add all the uio device file descriptor
> >  			 * into wait list.
> >  			 */
> >  			if (epoll_ctl(pfd, EPOLL_CTL_ADD,
> > -					src->intr_handle.fd, &ev) < 0){
> > +					src->intr_handle.fd, &ev) < 0)
> >  				rte_panic("Error adding fd %d epoll_ctl, %s\n",
> >  					src->intr_handle.fd, strerror(errno));
> > -			}
> > -			else
> > -				numfds++;
> > +
> > +			numfds++;
> >  		}
> >  		rte_spinlock_unlock(&intr_lock);
> >  		/* serve the interrupt */
> 
> 

Sure I thought Matthew would since he reported the issue and had the ability
to test it.

Re: [dpdk-dev] [PATCH] eal_interrupts.c: properly init struct epoll_event (valgrind)

[Matthew Hall]

On Thu, Mar 17, 2016 at 10:19:24AM -0700, Stephen Hemminger wrote:
> > > A better patch would be to move the data structure into the
> > > code block used, and get rid of the useless else (rte_panic never returns);
> > > and fix the indentation, and use C99 initialization which should make valgrind
> > > happier.
> > > 
> > > The moral is don't just slap memsets around

Hi guys,

As you probably read before, I am a security developer, not a low-level / 
kernel guy, and my DPDK work is spare time only. So I try to limit the scope 
of my DPDK patches where possible, to avoid making headaches for the full-time 
team to the minimum required. I can try to redo or refactor all this unrelated 
stuff in the code, but I wouldn't be as fast or accurate as you would.

Matthew.