From: Luis R. Rodriguez Date: Thu, 18 Jul 2013 23:40:55 +0000 (-0700) Subject: backports: backport drvdata = NULL core driver fixes X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=9f5876fa9cfb8cd6f450c200043ca7e31915f976;p=openwrt%2Fstaging%2Fblogic.git backports: backport drvdata = NULL core driver fixes The Linux kernel had tons of code which at times cleared the drvdata upon probe failure or release. There are however a bunch of drivers that didn't clear this. Commit 0998d063 implmented clearing this upon device_release_driver() and dealt with probe failure on driver_probe_device(). After this the kernel was cleaned up separately with *tons* of patches to remove all these driver specific settings given that the clearing is now done internally by the device core. Instead of ifdef'ing code back in for older code where it was properly in place backport this by piggy backing the new required code upon the calls used in place. There is a small race here upon device_release_driver() but we can live with that theoretical race. Due to the way we hack this backport we can't use a separate namespace as we have with other symbols. mcgrof@frijol ~/linux-stable (git::master)$ git describe --contains \ 0998d0631001288a5974afc0b2a5f568bcdecb4d v3.6-rc1~99^2~14^2~17 I count 65 patches implemented after this: mcgrof@frijol ~/linux-stable (git::master)$ git format-patch \ --grep="device-core: Ensure drvdata = NULL when no driver is bound" \ -o null-drv-fix v3.6-rc1~99^2~14^2~17.. TL;DR Alan Stern argued that perhaps applying this to backports wasn't a good idea given that evidence shows that the original patch actually exposed tons of bugs in driver code where they were doing the wrong thing. While this may be true if the original patch was a bad idea it should be reverted, and if a bug is found upstream, then by all means finding it through backports will only accelerate the pace at which we fix these exposed bugs. That is, if a bug is found due to this on backports then a respective fix for it should go upstream, not to backports. This is the benefit of providing backports releases: keep your users engaged on upstream fixes. Furthermore I am in hopes that perhaps we can SmPL'ify the bugs instead and in the future perhaps require SmPL to proove that the what the original patch was doing won't affect the inverse of what the patch was trying to do -- that is drivers doing the wrong thing. commit 0998d0631001288a5974afc0b2a5f568bcdecb4d Author: Hans de Goede Date: Wed May 23 00:09:34 2012 +0200 device-core: Ensure drvdata = NULL when no driver is bound 1) drvdata is for a driver to store a pointer to driver specific data 2) If no driver is bound, there is no driver specific data associated with the device 3) Thus logically drvdata should be NULL if no driver is bound. But many drivers don't clear drvdata on device_release, or set drvdata early on in probe and leave it set on probe error. Both of which results in a dangling pointer in drvdata. This patch enforce for drvdata to be NULL after device_release or on probe failure. Signed-off-by: Hans de Goede Signed-off-by: Greg Kroah-Hartman Tested with ckmake against next-20130618: 1 2.6.24 [ OK ] 2 2.6.25 [ OK ] 3 2.6.26 [ OK ] 4 2.6.27 [ OK ] 5 2.6.28 [ OK ] 6 2.6.29 [ OK ] 7 2.6.30 [ OK ] 8 2.6.31 [ OK ] 9 2.6.32 [ OK ] 10 2.6.33 [ OK ] 11 2.6.34 [ OK ] 12 2.6.35 [ OK ] 13 2.6.36 [ OK ] 14 2.6.37 [ OK ] 15 2.6.38 [ OK ] 16 2.6.39 [ OK ] 17 3.0.79 [ OK ] 18 3.1.10 [ OK ] 19 3.10-rc1 [ OK ] 20 3.2.45 [ OK ] 21 3.3.8 [ OK ] 22 3.4.46 [ OK ] 23 3.5.7 [ OK ] 24 3.6.11 [ OK ] 25 3.7.10 [ OK ] 26 3.8.13 [ OK ] 27 3.9.3 [ OK ] real 32m2.332s user 860m23.688s sys 121m20.840s Cc: Hans de Goede Cc: Julia Lawall Cc: linux-usb@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: Jiri Slaby Cc: Jiri Kosina Cc: Felix Fietkau Signed-off-by: Luis R. Rodriguez --- diff --git a/backport/backport-include/linux/device.h b/backport/backport-include/linux/device.h index c2f80e262c58..ba55d0ec8bff 100644 --- a/backport/backport-include/linux/device.h +++ b/backport/backport-include/linux/device.h @@ -176,4 +176,23 @@ extern int dev_set_name(struct device *dev, const char *name, ...) __attribute__((format(printf, 2, 3))); #endif +#if LINUX_VERSION_CODE <= KERNEL_VERSION(3,6,0) +#define driver_probe_device(__drv, __dev) \ +({ \ + int ret; \ + ret = (driver_probe_device)(__drv, __dev); \ + if (ret) \ + dev_set_drvdata(__dev, NULL); \ + return ret; \ +}) + +#define device_release_driver(__dev) \ +({ \ + (device_release_driver)(__dev); \ + device_lock(__dev); \ + dev_set_drvdata(__dev, NULL); \ + device_unlock(__dev); \ +}) +#endif /* LINUX_VERSION_CODE <= KERNEL_VERSION(3,6,0) */ + #endif /* __BACKPORT_DEVICE_H */