tracing: Remove igrab() iput() call from uprobes.c (61f94203) · Commits · 戴 / test

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>

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)

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