On Mon, Jan 14, 2013 at 08:16:44AM -0800, Greg Kroah-Hartman wrote: > On Mon, Jan 14, 2013 at 04:49:59PM +0100, Thierry Reding wrote: > > On Wed, Jan 09, 2013 at 10:23:52AM +0100, Thierry Reding wrote: > > > On Wed, Jan 09, 2013 at 01:19:39AM -0800, Dmitry Torokhov wrote: > > > > On Wed, Jan 09, 2013 at 08:07:45AM +0100, Thierry Reding wrote: > > > > > On Sun, Jan 06, 2013 at 11:57:48AM -0800, Dmitry Torokhov wrote: > > > > > > On Sun, Jan 06, 2013 at 08:27:39PM +0100, Thierry Reding wrote: > > > > > > > On Sat, Jan 05, 2013 at 12:06:58AM -0800, Dmitry Torokhov wrote: > > > > > > > > On Sat, Jan 05, 2013 at 01:15:08PM +0530, Laxman Dewangan wrote: > > > > > > > [...] > > > > > > > > > @@ -735,25 +738,16 @@ static int tegra_kbc_probe(struct platform_device *pdev) > > > > > > > > > spin_lock_init(&kbc->lock); > > > > > > > > > setup_timer(&kbc->timer, tegra_kbc_keypress_timer, (unsigned long)kbc); > > > > > > > > > > > > > > > > > > - res = request_mem_region(res->start, resource_size(res), pdev->name); > > > > > > > > > - if (!res) { > > > > > > > > > - dev_err(&pdev->dev, "failed to request I/O memory\n"); > > > > > > > > > - err = -EBUSY; > > > > > > > > > - goto err_free_mem; > > > > > > > > > - } > > > > > > > > > - > > > > > > > > > - kbc->mmio = ioremap(res->start, resource_size(res)); > > > > > > > > > + kbc->mmio = devm_request_and_ioremap(&pdev->dev, res); > > > > > > > > > if (!kbc->mmio) { > > > > > > > > > - dev_err(&pdev->dev, "failed to remap I/O memory\n"); > > > > > > > > > - err = -ENXIO; > > > > > > > > > - goto err_free_mem_region; > > > > > > > > > + dev_err(&pdev->dev, "Cannot request memregion/iomap address\n"); > > > > > > > > > + return -EADDRNOTAVAIL; > > > > > > > > > > > > > > > > Erm, no, -EBUSY please. > > > > > > > > > > > > > > EADDRNOTAVAIL is the canonical error for devm_request_and_ioremap() > > > > > > > failure. The kerneldoc comment in lib/devres.c even gives a short > > > > > > > example that uses this error code. > > > > > > > > > > > > I am sorry, but I do not consider a function that was added a little > > > > > > over a year ago as a canon. If you look at the uses of EADDRNOTAVAIL it > > > > > > is used predominantly in networking code to indicate that attempted > > > > > > _network_ address is not available. > > > > > > > > > > EBUSY might be misleading, though. devm_request_and_ioremap() can fail > > > > > in both the request_mem_region() and ioremap() calls. Furthermore it'd > > > > > be good to settle on a consistent error-code instead of doing it > > > > > differently depending on subsystem and/or driver. Currently the various > > > > > error codes used are: > > > > > > > > > > EBUSY, EADDRNOTAVAIL, ENXIO, ENOMEM, ENODEV, ENOENT, EINVAL, > > > > > EIO, EFAULT, EADDRINUSE > > > > > > > > > > Also if we can settle on one error code we should follow up with a patch > > > > > to make it consistent across the tree and also update that kerneldoc > > > > > comment. I volunteer to do that if nobody else steps up. I'm also Cc'ing > > > > > Wolfram (the original author), maybe he has some thoughts on this. > > > > > > > > > > > > > If you going to change all drivers make devm_request_and_ioremap() > > > > return ERR_PTR()-encoded errors and then we can differentiate what > > > > part of it failed. > > > > > > Yeah, that thought also crossed my mind. I'll give other people some > > > time to comment before hurling myself into preparing patches. > > > > I've prepared a patch that changes devm_request_and_ioremap() to return > > ERR_PTR()-encoded errors and adjusts all callers. As you can imagine it > > is a bit on the huge side. scripts/get_maintainer.pl lists 156 people > > and mailing lists. I've gone through the list, and as far as I can tell > > everyone on that list is actually affected by the patch, so there's not > > much potential for tuning it down. > > > > There is also the issue of whose tree this should go into. Unfortunately > > the patch can't be broken down into smaller chunks because it changes > > how the devm_request_and_ioremap() function's return value is handled in > > an incompatible way, so it won't be possible to gradually phase this in. > > Furthermore I can imagine that until the end of the release cycle new > > code may be added on which the same transformations need to be done. I > > have a semantic patch to do the bulk of the work, but quite a bit of > > coordination will be required. > > > > I'm adding Arnd and Greg on Cc, maybe they can advise on how best to > > handle this kind of patch. > > You should provide a "wrapper" function that does the correct return > value, convert drivers over to it, and then, when everyone is changed, > drop the old call. To change 156 different drivers all at once, in a > way that is not detectable by the compiler breaking the build, is not a > good thing to do at all. > > By doing it in this manner, it will take longer, but you can push the > patches through the different maintainer's trees. If they are slow, > I'll be glad to take the remaining patches in my driver-core tree to do > the final bits. It certainly sounds like a less complicated way to do it. But it also involves adding a function with a made up name and drop a function with a perfectly good name instead. I wouldn't even know what name to choose for the new API. Thierry
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