[dpdk-stable] [PATCH] [18.11] net/mlx5: use open/read/close for ib stats query

[Slava Ovsiienko]

OK, so, should I resend v2 with:
- no From: tag
- add [ upstream commit 00437823cb80b8fa87dbe61becc07bd42ee98549 ]

With best regards, Slava

> -----Original Message-----
> From: Kevin Traynor <ktraynor at redhat.com>
> Sent: Tuesday, December 8, 2020 14:07
> To: Slava Ovsiienko <viacheslavo at nvidia.com>; stable at dpdk.org
> Cc: mohsinshaikh at niometrics.com
> Subject: Re: [PATCH] [18.11] net/mlx5: use open/read/close for ib stats query
> 
> On 08/12/2020 11:34, Viacheslav Ovsiienko wrote:
> > From: Mohsin Shaikh <mohsinshaikh at niometrics.com>
> >
> > From: Mohsin Shaikh <mohsinshaikh at niometrics.com>
> >
> 
> Hi Slava, your patches are putting in duplicate From: tags ^ and missing
> upstream commit ids. Please add upstream commit ids so I don't have to find it
> for every patch. i.e.
> 
> [ upstream commit 00437823cb80b8fa87dbe61becc07bd42ee98549 ]
> 
> > fgets(3)/fread(3)/fscanf(3) etc. use mmap(2)/munmap(2) which leads to
> > TLB shutdown interrupts to all DPDK app cores including RX cores.
> > This can cause packet drops. Use read(2)/write(2) instead.
> >
> > Bugzilla ID: 440
> > Cc: stable at dpdk.org
> >
> 
> We can drop the stable tag as it's targetted to LTS branch anyway
> 
> > Signed-off-by: Mohsin Shaikh <mohsinshaikh at niometrics.com>
> > Reviewed-by: Alexander Kozyrev <akozyrev at mellanox.com>
> > Acked-by: Viacheslav Ovsiienko <viacheslavo at mellanox.com>
> > ---
> >  drivers/net/mlx5/mlx5_stats.c | 21 ++++++++++++++-------
> >  1 file changed, 14 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/net/mlx5/mlx5_stats.c
> > b/drivers/net/mlx5/mlx5_stats.c index 6906dc8..0b1fe3d 100644
> > --- a/drivers/net/mlx5/mlx5_stats.c
> > +++ b/drivers/net/mlx5/mlx5_stats.c
> > @@ -3,11 +3,13 @@
> >   * Copyright 2015 Mellanox Technologies, Ltd
> >   */
> >
> > +#include <fcntl.h>
> >  #include <inttypes.h>
> >  #include <linux/sockios.h>
> >  #include <linux/ethtool.h>
> >  #include <stdint.h>
> >  #include <stdio.h>
> > +#include <unistd.h>
> >
> >  #include <rte_ethdev_driver.h>
> >  #include <rte_common.h>
> > @@ -139,19 +141,24 @@
> >  static inline void
> >  mlx5_read_ib_stat(struct mlx5_priv *priv, const char *ctr_name,
> > uint64_t *stat)  {
> > -	FILE *file;
> > +	int fd;
> > +
> >  	MKSTR(path, "%s/ports/1/hw_counters/%s",
> >  		  priv->ibdev_path,
> >  		  ctr_name);
> >
> > -	file = fopen(path, "rb");
> > -	if (file) {
> > -		int n = fscanf(file, "%" SCNu64, stat);
> > +	fd = open(path, O_RDONLY);
> > +	if (fd != -1) {
> > +		char buf[21] = {'\0'};
> > +		ssize_t n = read(fd, buf, sizeof(buf));
> >
> > -		fclose(file);
> > -		if (n != 1)
> > -			stat = 0;
> > +		close(fd);
> > +		if (n != -1) {
> > +			*stat = strtoull(buf, NULL, 10);
> > +			return;
> > +		}
> >  	}
> > +	*stat = 0;
> >  }
> >
> >  /**
> >