[PATCH 2/7] tracing: Remove igrab() iput() call from uprobes.c
From: Steven Rostedt
Date: Wed May 02 2018 - 16:00:55 EST
From: Song Liu <songliubraving@xxxxxx>
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@xxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/20180423172135.4050588-2-songliubraving@xxxxxx
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Howard McLauchlan <hmclauchlan@xxxxxx>
Cc: Josef Bacik <jbacik@xxxxxx>
Cc: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx>
Acked-by: Miklos Szeredi <mszeredi@xxxxxxxxxx>
Signed-off-by: Song Liu <songliubraving@xxxxxx>
Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
---
kernel/events/uprobes.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index ce6848e46e94..1725b902983f 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -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)
--
2.17.0