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Commit 61f94203 authored by Song Liu's avatar Song Liu Committed by Steven Rostedt (VMware)
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tracing: Remove igrab() iput() call from uprobes.c 

Caller of uprobe_register is required to keep the inode and containing
mount point referenced.

There was misuse of igrab() in uprobes.c and trace_uprobe.c. This is
because igrab() will not prevent umount of the containing mount point.
To fix this, we added path to struct trace_uprobe, which keeps the inode
and containing mount reference.

For uprobes.c, it is not necessary to call igrab() in uprobe_register(),
as the caller is required to keep the inode reference. The igrab() is
removed and comments on this requirement is added to uprobe_register().

Link: http://lkml.kernel.org/r/CAELBmZB2XX=qEOLAdvGG4cPx4GEntcSnWQquJLUK1ongRj35cA@mail.gmail.com
Link: http://lkml.kernel.org/r/20180423172135.4050588-2-songliubraving@fb.com



Cc: Ingo Molnar <mingo@redhat.com>
Cc: Howard McLauchlan <hmclauchlan@fb.com>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Acked-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
Signed-off-by: default avatarSong Liu <songliubraving@fb.com>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent 0c92c7a3

kernel/events/uprobes.c

+3 −4
Original line number Diff line number Diff line
@@ -491,7 +491,7 @@ static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset) 
	if (!uprobe)

		return NULL;



	uprobe->inode = igrab(inode);

	uprobe->inode = inode;

	uprobe->offset = offset;

	init_rwsem(&uprobe->register_rwsem);

	init_rwsem(&uprobe->consumer_rwsem);
@@ -502,7 +502,6 @@ static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset) 
	if (cur_uprobe) {

		kfree(uprobe);

		uprobe = cur_uprobe;

		iput(inode);

	}



	return uprobe;
@@ -701,7 +700,6 @@ static void delete_uprobe(struct uprobe *uprobe) 
	rb_erase(&uprobe->rb_node, &uprobes_tree);

	spin_unlock(&uprobes_treelock);

	RB_CLEAR_NODE(&uprobe->rb_node); /* for uprobe_is_active() */

	iput(uprobe->inode);

	put_uprobe(uprobe);

}
@@ -873,7 +871,8 @@ static void __uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *u 
 * tuple).  Creation refcount stops uprobe_unregister from freeing the

 * @uprobe even before the register operation is complete. Creation

 * refcount is released when the last @uc for the @uprobe

 * unregisters.

 * unregisters. Caller of uprobe_register() is required to keep @inode

 * (and the containing mount) referenced.

 *

 * Return errno if it cannot successully install probes

 * else return 0 (success)