On Wed, Dec 7, 2022 at 3:49 PM Adrian Hunter <adrian.hunter@xxxxxxxxx> wrote: > On 7/12/22 15:25, Andy Shevchenko wrote: > > On Wed, Dec 7, 2022 at 3:01 PM Tomer Maimon <tmaimon77@xxxxxxxxx> wrote: > >> On Mon, 5 Dec 2022 at 16:33, Adrian Hunter <adrian.hunter@xxxxxxxxx> wrote: > >>> On 5/12/22 16:17, Andy Shevchenko wrote: > >>>> On Mon, Dec 5, 2022 at 4:14 PM Andy Shevchenko > >>>> <andy.shevchenko@xxxxxxxxx> wrote: > >>>>> On Mon, Dec 5, 2022 at 3:41 PM Adrian Hunter <adrian.hunter@xxxxxxxxx> wrote: > >>>>>> On 5/12/22 15:25, Andy Shevchenko wrote: > >>>>>>> On Mon, Dec 5, 2022 at 1:20 PM Tomer Maimon <tmaimon77@xxxxxxxxx> wrote: ... > >>>>>>> devm_ is problematic in your case. > >>>>>>> TL;DR: you need to use clk_get_optional() and clk_put(). > >>>>>> > >>>>>> devm_ calls exactly those, so what is the issue? > >>>>> > >>>>> The issue is the error path or removal stage where it may or may be > >>>>> not problematic. To be on the safe side, the best approach is to make > >>>>> sure that allocated resources are being deallocated in the reversed > >>>>> order. That said, the > >>>>> > >>>>> 1. call non-devm_func() > >>>>> 2. call devm_func() > >>>>> > >>>>> is wrong strictly speaking. > >>>> > >>>> To elaborate more, the > >>>> > >>>> 1. call all devm_func() > >>>> 2. call only non-devm_func() > >>>> > >>>> is the correct order. > >>> > >>> 1. WRT pltfm_host->clk, that is what is happening > >>> 2. WRT other resources that is simply not always possible because not every resource is wrapped by devm_ > >>> e.g. mmc_alloc_host() / mmc_free_host() > >> I little confused about what to decide, should I use only > >> non-devm_func because mmc_alloc_host() / mmc_free_host() is not > >> warrped with devm_? > > > > It is up to you how to proceed. I pointed out the problem with your > > code which may or may not be fatal. > > > > If you want to solve it, there are several approaches: > > 1) get rid of devm_ completely; > > 2) properly shuffle the ordering in ->probe(), so all devm_ calls are > > followed by non-devm_; > > 3) wrap non-devm_ cals to become managed (see > > devm_add_action_or_reset() approach); > > 4) fix SDHCI / MMC layer by providing necessary devm_ calls and/or fix > > sdhci_pltfm_register() to handle the clock. > > I can take care of sdhci_pltfm when I next have some time. > Otherwise it looks OK to me, so I am acking it. Thank you! > > Personally, the list order is from the least, what I prefer, to the > > most (i.o.w. I would like to see rather 4) than 1) to be implemented). > > > >>>> Hence in this case the driver can be worked around easily (by > >>>> shuffling the order in ->probe() to call devm_ first), but as I said > >>>> looking into implementation of the _unregister() I'm pretty sure that > >>>> clock management should be in sdhci-pltfm, rather than in all callers > >>>> who won't need the full customization. > >>>> > >>>> Hope this helps to understand my point. > >>>> > >>>>>>> Your ->remove() callback doesn't free resources in the reversed order > >>>>>>> which may or, by luck, may not be the case of all possible crashes, > >>>>>>> UAFs, races, etc during removal stage. All the same for error path in > >>>>>>> ->probe(). > >>>>> > >>>>> I also pointed out above what would be the outcome of neglecting this rule. ... > >>>>>>>>> Why can't you use sdhci_pltfm_register()? > >>>>>>>> two things are missing in sdhci_pltfm_register > >>>>>>>> 1. clock. > >>>>>>> > >>>>>>> Taking into account the implementation of the corresponding > >>>>>>> _unregister() I would add the clock handling to the _register() one. > >>>>>>> Perhaps via a new member of the platform data that supplies the name > >>>>>>> and index of the clock and hence all clk_get_optional() / clk_put will > >>>>>>> be moved there. > >> Do you mean to add it to sdhci_pltfm_register function? if yes I > >> believe it will take some time to modify sdhci_pltfm_register > >> I prefer not to use sdhci_pltfm_register. > > > > In the Linux kernel we are trying hard to avoid code duplication. Why > > do you need it to be open coded? (Yes, I heard you, but somebody > > should fix the issues with that funcion at some point, right?) > > > >>>>>>>> 2. Adding SDHCI_CAN_DO_8BIT capability according the eMMC capabilities. > >>>>>>> > >>>>>>> All the same, why can't platform data be utilised for this? -- With Best Regards, Andy Shevchenko
