| Message ID | 20220302011306.2054550-1-lv.ruyi@zte.com.cn (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | module: avoid calling synchronize_rcu() | expand |
Hi, On Wed, 2 Mar 2022, cgel.zte@gmail.com wrote: > From: Lv Ruyi (CGEL ZTE) <lv.ruyi@zte.com.cn> > > Kfree_rcu() usually results in even simpler code than does > synchronize_rcu() without synchronize_rcu()'s multi-millisecond > latency, so replace synchronize_rcu() with kfree_rcu(). > > Reported-by: Zeal Robot <zealci@zte.com.cn> > Signed-off-by: Lv Ruyi (CGEL ZTE) <lv.ruyi@zte.com.cn> > --- > kernel/module.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/kernel/module.c b/kernel/module.c > index 6cea788fd965..767b5f9e5819 100644 > --- a/kernel/module.c > +++ b/kernel/module.c > @@ -4138,8 +4138,7 @@ static int load_module(struct load_info *info, const char __user *uargs, > ddebug_cleanup: > ftrace_release_mod(mod); > dynamic_debug_remove(mod, info->debug); > - synchronize_rcu(); > - kfree(mod->args); > + kfree_rcu(mod->args); this has been proposed already. synchronize_rcu() and kfree() here are not really tied together. See the discussion at https://lore.kernel.org/all/alpine.LSU.2.21.2111301132220.3922@pobox.suse.cz/T/#u Regards Miroslav
On Wed, Mar 02, 2022 at 10:14:00AM +0100, Miroslav Benes wrote: > Hi, > > On Wed, 2 Mar 2022, cgel.zte@gmail.com wrote: > > > From: Lv Ruyi (CGEL ZTE) <lv.ruyi@zte.com.cn> > > > > Kfree_rcu() usually results in even simpler code than does > > synchronize_rcu() without synchronize_rcu()'s multi-millisecond > > latency, so replace synchronize_rcu() with kfree_rcu(). > > > > Reported-by: Zeal Robot <zealci@zte.com.cn> > > Signed-off-by: Lv Ruyi (CGEL ZTE) <lv.ruyi@zte.com.cn> > > --- > > kernel/module.c | 3 +-- > > 1 file changed, 1 insertion(+), 2 deletions(-) > > > > diff --git a/kernel/module.c b/kernel/module.c > > index 6cea788fd965..767b5f9e5819 100644 > > --- a/kernel/module.c > > +++ b/kernel/module.c > > @@ -4138,8 +4138,7 @@ static int load_module(struct load_info *info, const char __user *uargs, > > ddebug_cleanup: > > ftrace_release_mod(mod); > > dynamic_debug_remove(mod, info->debug); > > - synchronize_rcu(); > > - kfree(mod->args); > > + kfree_rcu(mod->args); > > this has been proposed already. synchronize_rcu() and kfree() here are not > really tied together. See the discussion at > https://lore.kernel.org/all/alpine.LSU.2.21.2111301132220.3922@pobox.suse.cz/T/#u Aaron, can you add a nice comment here to explain this while at it? Otherwise this will be lost tribal knowledge. Lv Ruyi, please open source your Zeal Robot. Thanks! Luis
diff --git a/kernel/module.c b/kernel/module.c index 6cea788fd965..767b5f9e5819 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -4138,8 +4138,7 @@ static int load_module(struct load_info *info, const char __user *uargs, ddebug_cleanup: ftrace_release_mod(mod); dynamic_debug_remove(mod, info->debug); - synchronize_rcu(); - kfree(mod->args); + kfree_rcu(mod->args); free_arch_cleanup: cfi_cleanup(mod); module_arch_cleanup(mod);