From: "Dumitrescu, Cristian" <cristian.dumitrescu@intel.com>
To: "Mrozowicz, SlawomirX" <slawomirx.mrozowicz@intel.com>,
"Jastrzebski, MichalX K" <michalx.k.jastrzebski@intel.com>,
"Zhang, Roy Fan" <roy.fan.zhang@intel.com>,
"Singh, Jasvinder" <jasvinder.singh@intel.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH v3] examples/qos_sched: fix bad bit shift operation
Date: Tue, 10 May 2016 09:45:36 +0000 [thread overview]
Message-ID: <3EB4FA525960D640B5BDFFD6A3D89126479BABDA@IRSMSX108.ger.corp.intel.com> (raw)
In-Reply-To: <158888A50F43E34AAE179517F56C97455A4600@IRSMSX103.ger.corp.intel.com>
> -----Original Message-----
> From: Mrozowicz, SlawomirX
> Sent: Tuesday, May 10, 2016 10:40 AM
> To: Dumitrescu, Cristian <cristian.dumitrescu@intel.com>; Jastrzebski,
> MichalX K <michalx.k.jastrzebski@intel.com>; Zhang, Roy Fan
> <roy.fan.zhang@intel.com>; Singh, Jasvinder <jasvinder.singh@intel.com>
> Cc: dev@dpdk.org
> Subject: RE: [PATCH v3] examples/qos_sched: fix bad bit shift operation
>
>
> >-----Original Message-----
> >From: Dumitrescu, Cristian
> >Sent: Thursday, April 28, 2016 1:16 PM
> >To: Jastrzebski, MichalX K <michalx.k.jastrzebski@intel.com>; Zhang, Roy
> Fan
> ><roy.fan.zhang@intel.com>; Singh, Jasvinder <jasvinder.singh@intel.com>
> >Cc: dev@dpdk.org; Mrozowicz, SlawomirX
> <slawomirx.mrozowicz@intel.com>
> >Subject: RE: [PATCH v3] examples/qos_sched: fix bad bit shift operation
> >
> >
> >
> >> -----Original Message-----
> >> From: Jastrzebski, MichalX K
> >> Sent: Thursday, April 21, 2016 2:08 PM
> >> To: Dumitrescu, Cristian <cristian.dumitrescu@intel.com>; Zhang, Roy
> >> Fan <roy.fan.zhang@intel.com>; Singh, Jasvinder
> >> <jasvinder.singh@intel.com>
> >> Cc: dev@dpdk.org; Mrozowicz, SlawomirX
> ><slawomirx.mrozowicz@intel.com>
> >> Subject: [PATCH v3] examples/qos_sched: fix bad bit shift operation
> >>
> >> From: Slawomir Mrozowicz <slawomirx.mrozowicz@intel.com>
> >>
> >> Fix issue reported by Coverity.
> >>
> >> Coverity ID 30690: Bad bit shift operation
> >> large_shift: In expression 1ULL << i, left shifting by more than 63
> >> bits has undefined behavior. The shift amount, i, is as much as 127.
> >>
> >> Fixes: de3cfa2c9823 ("sched: initial import")
> >>
> >> Signed-off-by: Slawomir Mrozowicz <slawomirx.mrozowicz@intel.com>
> >> ---
> >> examples/qos_sched/args.c | 84 +++++++++++++++++++++++++++++--
> ---
> >-
> >> ------------
> >> 1 file changed, 52 insertions(+), 32 deletions(-)
> >>
> >> diff --git a/examples/qos_sched/args.c b/examples/qos_sched/args.c
> >> index 3e7fd08..cd077ba 100644
> >> --- a/examples/qos_sched/args.c
> >> +++ b/examples/qos_sched/args.c
> >> @@ -53,7 +53,7 @@
> >>
> >> static uint32_t app_master_core = 1;
> >> static uint32_t app_numa_mask;
> >> -static uint64_t app_used_core_mask = 0;
> >> +static int app_used_core_mask[RTE_MAX_LCORE];
>
> Changed type of the app_used_core_mask variable to store up to
> RTE_MAX_LCORE cores information.
>
> >> static uint64_t app_used_port_mask = 0; static uint64_t
> >> app_used_rx_port_mask = 0; static uint64_t app_used_tx_port_mask =
> 0;
> >> @@ -115,22 +115,23 @@ static inline int str_is(const char *str, const char
> >*is)
> >> return strcmp(str, is) == 0;
> >> }
> >>
> >> -/* returns core mask used by DPDK */
> >> -static uint64_t
> >> -app_eal_core_mask(void)
> >> +/* compare used core with eal configuration,
> >> + returns:
> >> + 1 if equal
> >> + 0 if differ */
> >> +static int
> >> +app_eal_core_check(void)
> >> {
> >> - uint32_t i;
> >> - uint64_t cm = 0;
> >> + uint16_t i;
> >> + int ret = 1;
> >> struct rte_config *cfg = rte_eal_get_configuration();
> >>
> >> - for (i = 0; i < RTE_MAX_LCORE; i++) {
> >> - if (cfg->lcore_role[i] == ROLE_RTE)
> >> - cm |= (1ULL << i);
> >> + for (i = 0; i < RTE_MAX_LCORE && ret; i++) {
> >> + if ((cfg->lcore_role[i] == ROLE_RTE) !=
> >> app_used_core_mask[i])
> >> + ret = 0;
> >> }
> >>
> >> - cm |= (1ULL << cfg->master_lcore);
> >> -
> >> - return cm;
> >> + return ret;
> >> }
> >>
>
> Added tool function app_eal_core_check() to check compatibility used cores
> with information stored in configuration file. The function is used below.
> Removed not used function app_eal_core_mask()
>
> >>
> >> @@ -292,14 +293,9 @@ app_parse_flow_conf(const char *conf_str)
> >> app_used_tx_port_mask |= mask;
> >> app_used_port_mask |= mask;
> >>
> >> - mask = 1lu << pconf->rx_core;
> >> - app_used_core_mask |= mask;
> >> -
> >> - mask = 1lu << pconf->wt_core;
> >> - app_used_core_mask |= mask;
> >> -
> >> - mask = 1lu << pconf->tx_core;
> >> - app_used_core_mask |= mask;
> >> + app_used_core_mask[pconf->rx_core] = 1;
> >> + app_used_core_mask[pconf->wt_core] = 1;
> >> + app_used_core_mask[pconf->tx_core] = 1;
> >>
>
> Change method of set the mask on each used core according to change mask
> type.
>
> >> nb_pfc++;
> >>
> >> @@ -335,7 +331,7 @@ app_parse_args(int argc, char **argv)
> >> int option_index;
> >> const char *optname;
> >> char *prgname = argv[0];
> >> - uint32_t i, nb_lcores;
> >> + uint16_t i, j, k, nb_lcores;
> >>
> >> static struct option lgopts[] = {
> >> { "pfc", 1, 0, 0 },
> >> @@ -349,6 +345,9 @@ app_parse_args(int argc, char **argv)
> >> { NULL, 0, 0, 0 }
> >> };
> >>
> >> + for (i = 0; i < RTE_MAX_LCORE; i++)
> >> + app_used_core_mask[i] = 0;
> >> +
>
> Set initial value of the mask.
>
> >> /* initialize EAL first */
> >> ret = rte_eal_init(argc, argv);
> >> if (ret < 0)
> >> @@ -436,19 +435,40 @@ app_parse_args(int argc, char **argv)
> >> }
> >>
> >> /* check master core index validity */
> >> - for(i = 0; i <= app_master_core; i++) {
> >> - if (app_used_core_mask & (1u << app_master_core)) {
> >> - RTE_LOG(ERR, APP, "Master core index is not
> >> configured properly\n");
> >> - app_usage(prgname);
> >> - return -1;
> >> - }
> >> + if (app_used_core_mask[app_master_core] == 1) {
> >> + RTE_LOG(ERR, APP,
> >> + "Master core index is not configured properly\n");
> >> + app_usage(prgname);
> >> + return -1;
> >> }
>
> Changed method of checking if mask is present on master core.
>
> >> - app_used_core_mask |= 1u << app_master_core;
> >> + app_used_core_mask[app_master_core] = 1;
> >> +
>
> Changed method of set master core in mask.
>
> >> + if ((app_eal_core_check() == 0) ||
> >> + (app_master_core != rte_get_master_lcore())) {
> >> +
> >> + char used_hexstr[RTE_MAX_LCORE/4+1];
> >> + char conf_hexstr[RTE_MAX_LCORE/4+1];
> >> + int used_byte, conf_byte;
> >> + struct rte_config *cfg = rte_eal_get_configuration();
> >> +
> >> + for (i = 0; i < RTE_MAX_LCORE/4; i++) {
> >> + used_byte = 0;
> >> + conf_byte = 0;
> >> + for (j = 0; j < 3; j++) {
> >> + k = 4 * (RTE_MAX_LCORE/4 - i - 1) + j;
> >> + used_byte += app_used_core_mask[k] << j;
> >> + conf_byte +=
> >> + ((cfg->lcore_role[k] ==
> >> + ROLE_RTE)?1:0) << j;
> >> + }
> >> + sprintf(&used_hexstr[i], "%1x", used_byte);
> >> + sprintf(&conf_hexstr[i], "%1x", used_byte);
> >> + }
> >> +
> >> + RTE_LOG(ERR, APP, "EAL core mask not configured
> >> properly\n");
> >> + RTE_LOG(ERR, APP, " must be : %s\n", used_hexstr);
> >> + RTE_LOG(ERR, APP, " instead of: %s\n", conf_hexstr);
> >>
> >> - if ((app_used_core_mask != app_eal_core_mask()) ||
> >> - (app_master_core != rte_get_master_lcore())) {
> >> - RTE_LOG(ERR, APP, "EAL core mask not configured properly,
> >> must be %" PRIx64
> >> - " instead of %" PRIx64 "\n" ,
> >> app_used_core_mask, app_eal_core_mask());
> >> return -1;
> >> }
> >>
>
> Changed method of checking compatibility used cores with information
> stored in configuration file (the if statement).
> Extended information about wrong eal configuration to be more readable
> for the user (body of the true branch).
>
> >> --
> >> 1.9.1
> >
> >
> >Can you please explain the root issue?
> >
> >This patch contains way too much code for fixing a shift overflow issue, it is
> >basically a rework without explaining the issue or reason/benefit for the
> >rework.
> >
> >This approach does not look right to me, I am sure there is a better and
> >quicker way to fix the potential issue once we all understand it.
> >
>
> Hi Cristian
>
> The original problem reported in the Coverity happened in reality if there are
> used more then 64 lcores. I think we should fix it.
>
> Maximum possible value of lcores is 128 according to RTE_MAX_LCORE
> definition in configuration file.
> The problem happened because mask of the used lcores is stored in 64 bits.
> Exactly the variable app_used_core_mask has uint64_t type.
>
> To solve this problem I extended type of the variable app_used_core_mask
> to array size RTE_MAX_LCORE.
> In this case I should change all places where the variable was used. It is
> reason why I changed so much code.
> Detail description you can find inside the code above.
>
> Best Regards,
> Sławomir
>
>
>
This is a false problem, as we will never use more than 64 lcores with this application. The typical number of lcores used with this app is 3 or 6, with 12 as the absolute maximum when 4 x 3 lcores are used to handle 4 x 10GbE ports.
The fix you are looking for is a quick and straightforward way to limit the max number of lcores use d by this app to 64. Can you look for this type of solution, please?
Thanks,
Cristian
next prev parent reply other threads:[~2016-05-10 9:45 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-21 13:08 [dpdk-dev] [PATCH v3] examples/qos_sched: fix negative loop bound Michal Jastrzebski
2016-04-21 13:08 ` [dpdk-dev] [PATCH v3] examples/qos_sched: fix copy-paste error Michal Jastrzebski
2016-04-28 11:00 ` Dumitrescu, Cristian
2016-05-16 16:16 ` Thomas Monjalon
2016-04-21 13:08 ` [dpdk-dev] [PATCH v3] examples/qos_sched: fix bad bit shift operation Michal Jastrzebski
2016-04-28 11:16 ` Dumitrescu, Cristian
2016-05-10 9:39 ` Mrozowicz, SlawomirX
2016-05-10 9:45 ` Dumitrescu, Cristian [this message]
2016-04-28 10:59 ` [dpdk-dev] [PATCH v3] examples/qos_sched: fix negative loop bound Dumitrescu, Cristian
2016-05-16 16:02 ` Thomas Monjalon
2016-05-10 12:20 [dpdk-dev] [PATCH v3] examples/qos_sched: fix bad bit shift operation Slawomir Mrozowicz
2016-05-10 17:25 ` Dumitrescu, Cristian
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