From 6878e7de6af726de47f9f3bec649c3f49e786586 Mon Sep 17 00:00:00 2001 From: Dmitry Torokhov Date: Wed, 13 Sep 2017 16:29:48 -0700 Subject: [PATCH] driver core: suppress sending MODALIAS in UNBIND uevents The current udev rules cause modules to be loaded on all device events save for "remove". With the introduction of KOBJ_BIND/KOBJ_UNBIND this causes issues, as driver modules that have devices bound to their drivers get immediately reloaded, and it appears to the user that module unloading doe snot work. The standard udev matching rule is foillowing: ENV{MODALIAS}=="?*", RUN{builtin}+="kmod load $env{MODALIAS}" Given that MODALIAS data is not terribly useful for UNBIND event, let's zap it from the generated uevent environment until we get userspace updated with the correct udev rule that only loads modules on "add" event. Reported-by: Jakub Kicinski Tested-by: Jakub Kicinski Fixes: 1455cf8dbfd0 ("driver core: emit uevents when device is bound ...") Signed-off-by: Dmitry Torokhov Signed-off-by: Greg Kroah-Hartman --- lib/kobject_uevent.c | 49 ++++++++++++++++++++++++++++++++++++-------- 1 file changed, 41 insertions(+), 8 deletions(-) diff --git a/lib/kobject_uevent.c b/lib/kobject_uevent.c index e590523ea476..f237a09a5862 100644 --- a/lib/kobject_uevent.c +++ b/lib/kobject_uevent.c @@ -294,6 +294,26 @@ static void cleanup_uevent_env(struct subprocess_info *info) } #endif +static void zap_modalias_env(struct kobj_uevent_env *env) +{ + static const char modalias_prefix[] = "MODALIAS="; + int i; + + for (i = 0; i < env->envp_idx;) { + if (strncmp(env->envp[i], modalias_prefix, + sizeof(modalias_prefix) - 1)) { + i++; + continue; + } + + if (i != env->envp_idx - 1) + memmove(&env->envp[i], &env->envp[i + 1], + sizeof(env->envp[i]) * env->envp_idx - 1); + + env->envp_idx--; + } +} + /** * kobject_uevent_env - send an uevent with environmental data * @@ -409,16 +429,29 @@ int kobject_uevent_env(struct kobject *kobj, enum kobject_action action, } } - /* - * Mark "add" and "remove" events in the object to ensure proper - * events to userspace during automatic cleanup. If the object did - * send an "add" event, "remove" will automatically generated by - * the core, if not already done by the caller. - */ - if (action == KOBJ_ADD) + switch (action) { + case KOBJ_ADD: + /* + * Mark "add" event so we can make sure we deliver "remove" + * event to userspace during automatic cleanup. If + * the object did send an "add" event, "remove" will + * automatically generated by the core, if not already done + * by the caller. + */ kobj->state_add_uevent_sent = 1; - else if (action == KOBJ_REMOVE) + break; + + case KOBJ_REMOVE: kobj->state_remove_uevent_sent = 1; + break; + + case KOBJ_UNBIND: + zap_modalias_env(env); + break; + + default: + break; + } mutex_lock(&uevent_sock_mutex); /* we will send an event, so request a new sequence number */