On 09/18, Adriano Cordova wrote: > > prepare_uprobe() serializes its callers by taking consumer_rwsem for > writing. That rwsem protects the consumer list, not the instruction > copy. > > Give struct uprobe a dedicated prepare_mutex and use it instead. > > No functional change.
So why? Is it preparation for 2/2 ? At first glance it doesn't need this change... Please add more details. Oleg. > Signed-off-by: Adriano Cordova <[email protected]> > --- > kernel/events/uprobes.c | 8 +++++--- > 1 file changed, 5 insertions(+), 3 deletions(-) > > diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c > index 7709ea882477..686585539ebf 100644 > --- a/kernel/events/uprobes.c > +++ b/kernel/events/uprobes.c > @@ -64,6 +64,7 @@ struct uprobe { > refcount_t ref; > struct rw_semaphore register_rwsem; > struct rw_semaphore consumer_rwsem; > + struct mutex prepare_mutex; /* serializes prepare_uprobe() > */ > struct list_head pending_list; > struct list_head consumers; > struct inode *inode; /* Also hold a ref to inode */ > @@ -1007,6 +1008,7 @@ static struct uprobe *alloc_uprobe(struct inode *inode, > loff_t offset, > INIT_LIST_HEAD(&uprobe->consumers); > init_rwsem(&uprobe->register_rwsem); > init_rwsem(&uprobe->consumer_rwsem); > + mutex_init(&uprobe->prepare_mutex); > RB_CLEAR_NODE(&uprobe->rb_node); > refcount_set(&uprobe->ref, 1); > > @@ -1104,8 +1106,8 @@ static int prepare_uprobe(struct uprobe *uprobe, struct > file *file, > if (test_bit(UPROBE_COPY_INSN, &uprobe->flags)) > return ret; > > - /* TODO: move this into _register, until then we abuse this sem. */ > - down_write(&uprobe->consumer_rwsem); > + /* Serialize concurrent prepare_uprobe() calls from uprobe_mmap(). */ > + mutex_lock(&uprobe->prepare_mutex); > if (test_bit(UPROBE_COPY_INSN, &uprobe->flags)) > goto out; > > @@ -1125,7 +1127,7 @@ static int prepare_uprobe(struct uprobe *uprobe, struct > file *file, > set_bit(UPROBE_COPY_INSN, &uprobe->flags); > > out: > - up_write(&uprobe->consumer_rwsem); > + mutex_unlock(&uprobe->prepare_mutex); > > return ret; > } > -- > 2.51.0 >
