Commit d4d3ccc6 authored by Oleg Nesterov's avatar Oleg Nesterov
Browse files

uprobes: Kill uprobe->copy_mutex 



Now that ->register_rwsem is safe under ->mmap_sem we can kill
->copy_mutex and abuse down_write(&uprobe->consumer_rwsem).

This makes prepare_uprobe() even more ugly, but we should kill
it anyway.

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Acked-by: default avatarSrikar Dronamraju <srikar@linux.vnet.ibm.com>
parent bb929284

kernel/events/uprobes.c

+3 −4
Original line number Diff line number Diff line
@@ -91,7 +91,6 @@ struct uprobe { 
	atomic_t		ref;

	struct rw_semaphore	register_rwsem;

	struct rw_semaphore	consumer_rwsem;

	struct mutex		copy_mutex;	/* TODO: kill me and UPROBE_COPY_INSN */

	struct list_head	pending_list;

	struct uprobe_consumer	*consumers;

	struct inode		*inode;		/* Also hold a ref to inode */
@@ -450,7 +449,6 @@ static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset) 
	uprobe->offset = offset;

	init_rwsem(&uprobe->register_rwsem);

	init_rwsem(&uprobe->consumer_rwsem);

	mutex_init(&uprobe->copy_mutex);

	/* For now assume that the instruction need not be single-stepped */

	__set_bit(UPROBE_SKIP_SSTEP, &uprobe->flags);
@@ -578,7 +576,8 @@ static int prepare_uprobe(struct uprobe *uprobe, struct file *file, 
	if (test_bit(UPROBE_COPY_INSN, &uprobe->flags))

		return ret;



	mutex_lock(&uprobe->copy_mutex);

	/* TODO: move this into _register, until then we abuse this sem. */

	down_write(&uprobe->consumer_rwsem);

	if (test_bit(UPROBE_COPY_INSN, &uprobe->flags))

		goto out;
@@ -602,7 +601,7 @@ static int prepare_uprobe(struct uprobe *uprobe, struct file *file, 
	set_bit(UPROBE_COPY_INSN, &uprobe->flags);



 out:

	mutex_unlock(&uprobe->copy_mutex);

	up_write(&uprobe->consumer_rwsem);



	return ret;

}

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