> -----Original Message----- > From: Ulf Hansson [mailto:ulf.hansson@xxxxxxxxxx] > Sent: Monday, May 22, 2017 3:05 PM > To: Linus Walleij <linus.walleij@xxxxxxxxxx> > Cc: linux-mmc@xxxxxxxxxxxxxxx; Adrian Hunter <adrian.hunter@xxxxxxxxx>; > linux-block@xxxxxxxxxxxxxxx; Jens Axboe <axboe@xxxxxxxxx>; Christoph > Hellwig <hch@xxxxxx>; Arnd Bergmann <arnd@xxxxxxxx>; Bartlomiej > Zolnierkiewicz <b.zolnierkie@xxxxxxxxxxx>; Paolo Valente > <paolo.valente@xxxxxxxxxx>; Avri Altman <Avri.Altman@xxxxxxxxxxx> > Subject: Re: [PATCH 0/6] More MMC block core refactorings > > On 19 May 2017 at 15:37, Linus Walleij <linus.walleij@xxxxxxxxxx> wrote: > > This series builds on top of the previous series that created custom > > DRV_OP requests for ioctl() operations in MMC. > > > > The first patch is a suggestion from Christoph, the second builds > > infrastructure for issuing more, currently orthogonal custom > > operations through the block layer. > > > > The first operation we move over is pretty uncontroversial and > > straight-forward: it is the operation that write-protect-locks the > > boot partitions from sysfs. This is now done through the block layer > > so we do not need to congest and starve in the big MMC lock. > > > > The last two patches are more contoversial: they move the two debugfs > > accesses for reading card status and EXT CSD over to using the block > > layer funnel *if* *present*. > > > > So if the block layer is configured out, these will still issue > > operations directly and take the big MMC lock. > > > > The patch series is fully ABI safe: any scripts or code using the > > debugfs with or without the block layer will still work. > > > > However this leaves the mmc_card_get() locks in the block.h header for > > the !CONFIG_MMC_BLOCK case and I'm not really happy to keep them > > around, the idea is to terminate them. > > > > Ways forward after these patches: > > > > - Simply remove the debugfs files for status and ext_csd if > > the block layer is not there. The debugfs is not ABI after > > all, and there is an ioctl() to do the same job, and > > that is what mmc-utils is using. > > > > - Simply remove the debugfs files for status and ext_csd > > completely - and require users to switch to using the > > ioctl() mmc-utils way of doing things if they want to > > inspect their MMC/SD cards. > > I like this approach. > > mmc-utils is also far better in parsing the results from ext csd and presents > the output in a more human readable format. > > Moreover, people that needs to debug the behavior of a card should likely > not have a problem with using mmc-utils. Those debugfs entries are there for ages, and there are some user-space utilities, e.g. for benchmarking etc. that count on it being there, as the key identification criteria if a mmc device is present. > > > > > - Wait and see: when I get to removing the big MMC lock from > > SDIO I will anyway have to deal with this mess since > > the big lock is no more a block layer problem, but a > > problem with the entire MMC/SD/SDIO stack. > > > > In any case: these patches fixes the starvation of the boot partition > > locking and the debugfs access when using the block layer heavily at > > the same time. > > > > Linus Walleij (6): > > mmc: block: remove req back pointer > > mmc: block: Tag DRV_OPs with a driver operation type > > mmc: block: Move DRV OP issue function > > mmc: block: Move boot partition locking into a driver op > > mmc: debugfs: Move card status retrieveal into the block layer > > mmc: debugfs: Move EXT CSD debugfs acces to block layer > > > > drivers/mmc/core/block.c | 168 > ++++++++++++++++++++++++++++++++------------- > > drivers/mmc/core/block.h | 49 +++++++++++++ > > drivers/mmc/core/debugfs.c | 19 +---- > > drivers/mmc/core/queue.c | 13 ++-- > > drivers/mmc/core/queue.h | 27 +++++++- > > 5 files changed, 200 insertions(+), 76 deletions(-) > > > > -- > > 2.9.3 > > > > I decided to pick patch 1->4 at this stage as those looks nice and clean. The > rest will need a re-spin. > > Thanks and kind regards > Uffe
