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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: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Song Liu 2018-04-23 10:21:35 -07:00 committed by Steven Rostedt (VMware)
parent 0c92c7a3c5
commit 61f94203c9
1 changed files with 3 additions and 4 deletions
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7
kernel/events/uprobes.c
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@ -491,7 +491,7 @@ static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset)
if (!uprobe) if (!uprobe)
return NULL; return NULL;
uprobe->inode = igrab(inode); uprobe->inode = inode;
uprobe->offset = offset; uprobe->offset = offset;
init_rwsem(&uprobe->register_rwsem); init_rwsem(&uprobe->register_rwsem);
init_rwsem(&uprobe->consumer_rwsem); init_rwsem(&uprobe->consumer_rwsem);
@ -502,7 +502,6 @@ static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset)
if (cur_uprobe) { if (cur_uprobe) {
kfree(uprobe); kfree(uprobe);
uprobe = cur_uprobe; uprobe = cur_uprobe;
iput(inode);
} }
return uprobe; return uprobe;
@ -701,7 +700,6 @@ static void delete_uprobe(struct uprobe *uprobe)
rb_erase(&uprobe->rb_node, &uprobes_tree); rb_erase(&uprobe->rb_node, &uprobes_tree);
spin_unlock(&uprobes_treelock); spin_unlock(&uprobes_treelock);
RB_CLEAR_NODE(&uprobe->rb_node); /* for uprobe_is_active() */ RB_CLEAR_NODE(&uprobe->rb_node); /* for uprobe_is_active() */
iput(uprobe->inode);
put_uprobe(uprobe); 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 * tuple). Creation refcount stops uprobe_unregister from freeing the
* @uprobe even before the register operation is complete. Creation * @uprobe even before the register operation is complete. Creation
* refcount is released when the last @uc for the @uprobe * 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 * Return errno if it cannot successully install probes
* else return 0 (success) * else return 0 (success)