user/sven/linux.git/include/linux/kobject.h, branch v3.18.74

kobject: Make support for uevent_helper optional.

2014-04-25T19:00:49Z

Support for uevent_helper, aka hotplug, is not required on many systems these days but it can still be enabled via sysfs or sysctl. Reported-by: Darren Shepherd Signed-off-by: Michael Marineau Signed-off-by: Greg Kroah-Hartman

kobject: don't block for each kobject_uevent

2014-04-03T23:21:04Z

Currently kobject_uevent has somewhat unpredictable semantics. The point is, since it may call a usermode helper and wait for it to execute (UMH_WAIT_EXEC), it is impossible to say for sure what lock dependencies it will introduce for the caller - strictly speaking it depends on what fs the binary is located on and the set of locks fork may take. There are quite a few kobject_uevent's users that do not take this into account and call it with various mutexes taken, e.g. rtnl_mutex, net_mutex, which might potentially lead to a deadlock. Since there is actually no reason to wait for the usermode helper to execute there, let's make kobject_uevent start the helper asynchronously with the aid of the UMH_NO_WAIT flag. Personally, I'm interested in this, because I really want kobject_uevent to be called under the slab_mutex in the slub implementation as it used to be some time ago, because it greatly simplifies synchronization and automatically fixes a kmemcg-related race. However, there was a deadlock detected on an attempt to call kobject_uevent under the slab_mutex (see https://lkml.org/lkml/2012/1/14/45), which was reported to be fixed by releasing the slab_mutex for kobject_uevent. Unfortunately, there was no information about who exactly blocked on the slab_mutex causing the usermode helper to stall, neither have I managed to find this out or reproduce the issue. BTW, this is not the first attempt to make kobject_uevent use UMH_NO_WAIT. Previous one was made by commit f520360d93cd ("kobject: don't block for each kobject_uevent"), but it was wrong (it passed arguments allocated on stack to async thread) so it was reverted in 05f54c13cd0c ("Revert "kobject: don't block for each kobject_uevent"."). It targeted on speeding up the boot process though. Signed-off-by: Vladimir Davydov Cc: Greg KH Cc: Christoph Lameter Cc: Pekka Enberg Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

kernfs: s/sysfs_dirent/kernfs_node/ and rename its friends accordingly

2013-12-11T23:28:36Z

kernfs has just been separated out from sysfs and we're already in full conflict mode. Nothing can make the situation any worse. Let's take the chance to name things properly. This patch performs the following renames. * s/sysfs_elem_dir/kernfs_elem_dir/ * s/sysfs_elem_symlink/kernfs_elem_symlink/ * s/sysfs_elem_attr/kernfs_elem_file/ * s/sysfs_dirent/kernfs_node/ * s/sd/kn/ in kernfs proper * s/parent_sd/parent/ * s/target_sd/target/ * s/dir_sd/parent/ * s/to_sysfs_dirent()/rb_to_kn()/ * misc renames of local vars when they conflict with the above Because md, mic and gpio dig into sysfs details, this patch ends up modifying them. All are sysfs_dirent renames and trivial. While we can avoid these by introducing a dummy wrapping struct sysfs_dirent around kernfs_node, given the limited usage outside kernfs and sysfs proper, I don't think such workaround is called for. This patch is strictly rename only and doesn't introduce any functional difference. - mic / gpio renames were missing. Spotted by kbuild test robot. Signed-off-by: Tejun Heo Cc: Neil Brown Cc: Linus Walleij Cc: Ashutosh Dixit Cc: kbuild test robot Signed-off-by: Greg Kroah-Hartman

sysfs: remove ktype->namespace() invocations in directory code

2013-09-26T22:30:22Z

For some unrecognizable reason, namespace information is communicated to sysfs through ktype->namespace() callback when there's *nothing* which needs the use of a callback. The whole sequence of operations is completely synchronous and sysfs operations simply end up calling back into the layer which just invoked it in order to find out the namespace information, which is completely backwards, obfuscates what's going on and unnecessarily tangles two separate layers. This patch doesn't remove ktype->namespace() but shifts its handling to kobject layer. We probably want to get rid of the callback in the long term. This patch adds an explicit param to sysfs_{create|rename|move}_dir() and renames them to sysfs_{create|rename|move}_dir_ns(), respectively. ktype->namespace() invocations are moved to the calling sites of the above functions. A new helper kboject_namespace() is introduced which directly tests kobj_ns_type_operations->type which should give the same result as testing sysfs_fs_type(parent_sd) and returns @kobj's namespace tag as necessary. kobject_namespace() is extern as it will be used from another file in the following patches. This patch should be an equivalent conversion without any functional difference. Signed-off-by: Tejun Heo Cc: Eric W. Biederman Cc: Kay Sievers Signed-off-by: Greg Kroah-Hartman

kobject: delayed kobject release: help find buggy drivers

2013-07-25T22:39:04Z

Implement debugging for kobject release functions. kobjects are reference counted, so the drop of the last reference to them is not predictable. However, the common case is for the last reference to be the kobject's removal from a subsystem, which results in the release function being immediately called. This can hide subtle bugs, which can occur when another thread holds a reference to the kobject at the same time that a kobject is removed. This results in the release method being delayed. In order to make these kinds of problems more visible, the following patch implements a delayed release; this has the effect that the release function will be out of order with respect to the removal of the kobject in the same manner that it would be if a reference was being held. This provides us with an easy way to allow driver writers to debug their drivers and fix otherwise hidden problems. Signed-off-by: Russell King Signed-off-by: Greg Kroah-Hartman

kobject: remove CONFIG_HOTPLUG ifdefs

2012-11-28T18:33:03Z

Remove conditional code based on CONFIG_HOTPLUG being false. It's always on now in preparation of it going away as an option. Signed-off-by: Bill Pemberton Signed-off-by: Greg Kroah-Hartman

kobject: fix oops with "input0: bad kobj_uevent_env content in show_uevent()"

2012-09-06T17:13:58Z

Fengguang Wu writes: > After the __devinit* removal series, I can still get kernel panic in > show_uevent(). So there are more sources of bug.. > > Debug patch: > > @@ -343,8 +343,11 @@ static ssize_t show_uevent(struct device > goto out; > > /* copy keys to file */ > - for (i = 0; i < env->envp_idx; i++) > + dev_err(dev, "uevent %d env[%d]: %s/.../%s\n", env->buflen, env->envp_idx, top_kobj->name, dev->kobj.name); > + for (i = 0; i < env->envp_idx; i++) { > + printk(KERN_ERR "uevent %d env[%d]: %s\n", (int)count, i, env->envp[i]); > count += sprintf(&buf[count], "%s\n", env->envp[i]); > + } > > Oops message, the env[] is again not properly initilized: > > [ 44.068623] input input0: uevent 61 env[805306368]: input0/.../input0 > [ 44.069552] uevent 0 env[0]: (null) This is a completely different CONFIG_HOTPLUG problem, only demonstrating another reason why CONFIG_HOTPLUG should go away. I had a hard time trying to disable it anyway ;-) The problem this time is lots of code assuming that a call to add_uevent_var() will guarantee that env->buflen > 0. This is not true if CONFIG_HOTPLUG is unset. So things like this end up overwriting env->envp_idx because the array index is -1: if (add_uevent_var(env, "MODALIAS=")) return -ENOMEM; len = input_print_modalias(&env->buf[env->buflen - 1], sizeof(env->buf) - env->buflen, dev, 0); Don't know what the best action is, given that there seem to be a *lot* of this around the kernel. This patch "fixes" the problem for me, but I don't know if it can be considered an appropriate fix. [ It is the correct fix for now, for 3.7 forcing CONFIG_HOTPLUG to always be on is the longterm fix, but it's too late for 3.6 and older kernels to resolve this that way - gregkh ] Reported-by: Fengguang Wu Signed-off-by: Bjørn Mork Tested-by: Fengguang Wu Cc: stable Signed-off-by: Greg Kroah-Hartman

kobject: remove kset_find_obj_hinted()

2011-12-21T23:13:54Z

Now that there are no in-kernel users of this function, remove it as it is no longer needed. Signed-off-by: Kay Sievers Signed-off-by: Greg Kroah-Hartman

treewide: use printf not attribute__((format(printf,...)))

2011-11-01T00:30:54Z

Standardize the style for compiler based printf format verification. Standardized the location of __printf too. Done via script and a little typing. $ grep -rPl --include=*.[ch] -w "__attribute__" * | \ grep -vP "^(tools|scripts|include/linux/compiler-gcc.h)" | \ xargs perl -n -i -e 'local $/; while (<>) { s/\b__attribute__\s*$\s*\(\s*format\s*\(\s*printf\s*,\s*(.+)\s*,\s*(.+)\s*$\s*\)\s*\)/__printf($1, $2)/g ; print; }' [akpm@linux-foundation.org: revert arch bits] Signed-off-by: Joe Perches Cc: "Kirill A. Shutemov" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

atomic: use

2011-07-26T23:49:47Z

This allows us to move duplicated code in (atomic_inc_not_zero() for now) to Signed-off-by: Arun Sharma Reviewed-by: Eric Dumazet Cc: Ingo Molnar Cc: David Miller Cc: Eric Dumazet Acked-by: Mike Frysinger Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds