Hi

From: Stephen Hemminger
> On Tue, 30 Jul 2019 09:21:02 +0000
> Matan Azrad <ma...@mellanox.com> wrote:
> 
> > Hi Stephen
> >
> > From:  Stephen Hemminger
> > > From: Stephen Hemminger <sthem...@microsoft.com>
> > >
> > > The mp_server incorrectly allows a port mask that included hidden
> > > ports and which later caused either lost packets or failed initialization.
> > >
> > > This fixes explicitly checking that each bit in portmask is a valid
> > > port before using it.
> > >
> > > Fixes: 5b7ba31148a8 ("ethdev: add port ownership")
> > > Signed-off-by: Stephen Hemminger <sthem...@microsoft.com>
> > > ---
> > >  .../client_server_mp/mp_server/args.c         | 46 +++++++++++++------
> > >  .../client_server_mp/mp_server/args.h         |  2 +-
> > >  .../client_server_mp/mp_server/init.c         |  7 +--
> > >  3 files changed, 35 insertions(+), 20 deletions(-)
> > >
> > > diff --git
> > > a/examples/multi_process/client_server_mp/mp_server/args.c
> > > b/examples/multi_process/client_server_mp/mp_server/args.c
> > > index b0d8d7665c85..c1ab12ad00d1 100644
> > > --- a/examples/multi_process/client_server_mp/mp_server/args.c
> > > +++ b/examples/multi_process/client_server_mp/mp_server/args.c
> > > @@ -10,6 +10,7 @@
> > >  #include <errno.h>
> > >
> > >  #include <rte_memory.h>
> > > +#include <rte_ethdev.h>
> > >  #include <rte_string_fns.h>
> > >
> > >  #include "common.h"
> > > @@ -34,6 +35,22 @@ usage(void)
> > >       , progname);
> > >  }
> > >
> > > +/**
> > > + * Check if port is present in the system
> > > + * It maybe owned by a device and should not be used.
> > > + */
> > > +static int
> > > +port_is_present(uint16_t portid)
> > > +{
> > > + uint16_t id;
> > > +
> > > + RTE_ETH_FOREACH_DEV(id) {
> > > +         if (id == portid)
> > > +                 return 1;
> > > + }
> > > + return 0;
> > > +}
> > > +
> > >  /**
> > >   * The ports to be used by the application are passed in
> > >   * the form of a bitmask. This function parses the bitmask @@
> > > -41,31 +58,32 @@ usage(void)
> > >   * array variable
> > >   */
> > >  static int
> > > -parse_portmask(uint8_t max_ports, const char *portmask)
> > > +parse_portmask(const char *portmask)
> > >  {
> > >   char *end = NULL;
> > >   unsigned long pm;
> > > - uint16_t count = 0;
> > > + uint16_t count;
> > >
> > >   if (portmask == NULL || *portmask == '\0')
> > >           return -1;
> > >
> > >   /* convert parameter to a number and verify */
> > >   pm = strtoul(portmask, &end, 16);
> > > - if (end == NULL || *end != '\0' || pm == 0)
> > > + if (end == NULL || *end != '\0' || pm > UINT16_MAX || pm == 0)
> > >           return -1;
> > >
> > >   /* loop through bits of the mask and mark ports */
> > > - while (pm != 0){
> > > -         if (pm & 0x01){ /* bit is set in mask, use port */
> > > -                 if (count >= max_ports)
> > > -                         printf("WARNING: requested port %u not
> > > present"
> > > -                         " - ignoring\n", (unsigned)count);
> > > -                 else
> > > -                     ports->id[ports->num_ports++] = count;
> > > + for (count = 0; pm != 0; pm >>= 1, ++count) {
> > > +         if ((pm & 0x1) == 0)
> > > +                 continue;
> > > +
> > > +         if (!port_is_present(count)) {
> > > +                 printf("WARNING: requested port %u not present -
> > > ignoring\n",
> > > +                         count);
> > > +                 continue;
> > >           }
> > > -         pm = (pm >> 1);
> > > -         count++;
> > > +
> > > +         ports->id[ports->num_ports++] = count;
> > >   }
> >
> > Why not just to do something like:
> >
> > RTE_ETH_FOREACH_DEV(id) {
> >     If (pm & (1 << id)) {
> >             pm &= ~(1 << id)
> >             put in list
> >     }
> > }
> >     If (pm)
> >             Warning
> >
> 
> No real reason, was just trying to keep existing logic flow

This is an example for the users\developers, and you on it,
I think this is a good chance to show how to do it in the correct way - O(n) 
instead O(n^2).

Don't you think so?
 
I suggest to adjust. 

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