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. 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
