Hi Jason, Jim, On 6/18/20 10:40 PM, Jason Baron wrote: > > > On 6/18/20 3:11 PM, jim.cromie@xxxxxxxxx wrote: >> On Thu, Jun 18, 2020 at 12:17 PM Jason Baron <jbaron@xxxxxxxxxx> wrote: >>> >>> >>> >>> On 6/18/20 1:40 PM, Petr Mladek wrote: >>>> On Thu 2020-06-18 18:19:12, Petr Mladek wrote: >>>>> On Wed 2020-06-17 10:25:35, Jim Cromie wrote: >>>>>> 1. Add a user-flag [u] which works like the [pfmlt] flags, but has no >>>>>> effect on callsite behavior; it allows incremental marking of >>>>>> arbitrary sets of callsites. >>>>>> >>>>>> 2. Add [PFMLTU] flags, which negate their counterparts; P===!p etc. >>>>>> And in ddebug_read_flags(): >>>>>> current code does: [pfmltu_] -> flags >>>>>> copy it to: [PFMLTU_] -> mask >>>>>> >>>>>> also disallow both of a pair: ie no 'pP', no true & false. >>>>>> >>>>>> 3. Add filtering ops into ddebug_change(), right after all the >>>>>> callsite-property selections are complete. These filter on the >>>>>> callsite's current flagstate before applying modflags. >>>>>> >>>>>> Why ? >>>>>> >>>>>> The u-flag & filter flags >>>>>> >>>>>> The 'u' flag lets the user assemble an arbitary set of callsites. >>>>>> Then using filter flags, user can activate the 'u' callsite set. >>>>>> >>>>>> #> echo 'file foo.c +u; file bar.c +u' > control # and repeat >>>>>> #> echo 'u+p' > control >>>>>> >>>>>> Of course, you can continue to just activate your set without ever >>>>>> marking it 1st, but you could trivially add the markup as you go, then >>>>>> be able to use it as a constraint later, to undo or modify your set. >>>>>> >>>>>> #> echo 'file foo.c +up' >control >>>>>> .. monitor, debug, finish .. >>>>>> #> echo 'u-p' >control >>>>>> >>>>>> # then later resume >>>>>> #> echo 'u+p' >control >>>>>> >>>>>> # disable some cluttering messages, and remove from u-set >>>>>> #> echo 'file noisy.c function:jabber_* u-pu' >control >>>>>> >>>>>> # for doc, recollection >>>>>> grep =pu control > my-favorite-callsites >>>>>> >>>>>> Note: >>>>>> >>>>>> Your flagstate after boot is generally not all =_. -DDEBUG will arm >>>>>> compiled callsites by default, $builtinmod.dyndbg=+p bootargs can >>>>>> enable them early, and $module.dyndbg=+p bootargs will arm them when >>>>>> the module is loaded. But you could manage them with u-flags: >>>>>> >>>>>> #> echo '-t' >control # clear t-flag to use it as 2ndary markup >>>>>> #> echo 'p+ut' >control # mark the boot-enabled set of callsites >>>>>> #> echo '-p' >control # clean your dmesg -w stream >>>>>> >>>>>> ... monitor, debug .. >>>>>> #> echo 'module of_interest $qterms +pu' >control # build your set of useful debugs >>>>>> #> echo 'module of_interest $qterms UT+pu' >control # same, but dont alter ut marked set >>>>> >>>>> Does anyone requested this feature, please? >>>>> >>>>> For me, it is really hard to imagine people using these complex and hacky >>>>> steps. >>>> >>>> I think that all this is motivated by adding support for module >>>> specific groups. >>>> >>>> What about storing the group as yet another information for each >>>> message? I mean the same way as we store module name, file, line, >>>> function name. >>>> >>>> Then we could add API to define group for a given message: >>>> >>>> pr_debug_group(group_id, fmt, ...); >>>> >>>> the interface for the control file might be via new keyword "group". >>>> You could then do something like: >>>> >>>> echo module=drm group=0x3 +p >control >>>> >>>> But more importantly you should add functions that might be called >>>> when the drm.debug parameter is changes. I have already mentioned >>>> it is another reply: >>>> >>>> dd_enable_module_group(module_name, group_id); >>>> dd_disable_module_group(module_name, group_id); >>>> >>>> >>>> It will _not_ need any new flag or flag filtering. >>>> >>>> Best Regards, >>>> Petr >>>> >>> >>> Yes, I'm wondering as well if people are really going to use the >>> new flags and filter flags - I mentioned that here: >>> https://urldefense.proofpoint.com/v2/url?u=https-3A__lkml.org_lkml_2020_6_12_732&d=DwIBaQ&c=96ZbZZcaMF4w0F4jpN6LZg&r=1fLh1mlLqbfetnnGsbwXfpwmGlG4m83mXgtV4vZ1B1A&m=vltk6sSzPDQIqO4gGkJeDY6jcEarG4xTztab2EHtPFY&s=6x1EHNoRxebA99Tu-C2i0s5dmdzyEF9bXVcv_cYoM_I&e= >>> >> >> yes, I saw, and replied there. >> but since that was v1, and we're on v3, we should refresh. >> >> the central use-case is above, 1-liner version summarized here: >> >> 1- enable sites as you chase a problem with +up >> 2- examine them with grep =pu >> 3- change the set to suit, either by adding or subtracting callsites. >> 4- continue debugging, and changing callsites to suit >> 5- grep =pu control > ~/debugging-session-task1-callsites >> 6- echo up-p >control # disable for now, leave u-set for later >> 7- do other stuff >> 8 echo uP+p >control # reactivate useful debug-state and resume >> >> >>> The grouping stuff is already being used by lots of modules so >>> that seems useful. >> >> I now dont see the need. >> >> given N debug callsites, any group can be defined by <N queries, >> probably a lot less >> if module authors can use ddebug_exec_queries(), cuz its exported, (15/21) >> then they can act (+p or -p) on those sets defined by <N queries. >> >> and now any callsite can be in any number of groups, not just one. >> It would be prudent to evaluate such groupings case by case, >> because the intersecting callsites are subject to "last manipulator wins" >> but its unnecessary to insist that all sets are disjoint. >> Unlike pr_debug_n, however its spelled. >> > > hmm - so I think you are saying there is then no need to change the > calling functions themselves - its still 'pr_debug()'. You could even > use the 'format' qualifier for example to implement your groups that > way. > > For example: > > pr_debug("failure type1: blah"); > pr_debug("failure type2: blah blah"); > > and then do: ddebug_exec_queries("format type1 +p", module); > > I would be curious to see what Stanimir thinks of this proposal > and whether it would work for his venus driver, which is what > prompted this module group discussion. Hmm, we spin in a circle :) Infact this was my first way of implementing the groups in Venus driver, you can see it at [1]. +#define VDBGL(fmt, args...) pr_debug("VENUSL: " fmt, ##args) +#define VDBGM(fmt, args...) pr_debug("VENUSM: " fmt, ##args) +#define VDBGH(fmt, args...) pr_debug("VENUSH: " fmt, ##args) +#define VDBGFW(fmt, args...) pr_debug("VENUSFW: " fmt, ##args) [1] https://lkml.org/lkml/2020/5/21/668 -- regards, Stan
