Commit 09eeb072 authored by Shyam Prasad N's avatar Shyam Prasad N Committed by Steve French
Browse files

cifs: do not depend on release_iface for maintaining iface_list 



parse_server_interfaces should be in complete charge of maintaining
the iface_list linked list. Today, iface entries are removed
from the list only when the last refcount is dropped.
i.e. in release_iface. However, this can result in undercounting
of refcount if the server stops advertising interfaces (which
Azure SMB server does).

This change puts parse_server_interfaces in full charge of
maintaining the iface_list. So if an empty list is returned
by the server, the entries in the list will immediately be
removed. This way, a following call to the same function will
not find entries in the list.

Fixes: aa45dadd ("cifs: change iface_list from array to sorted linked list")
Cc: stable@vger.kernel.org
Signed-off-by: default avatarShyam Prasad N <sprasad@microsoft.com>
Signed-off-by: default avatarSteve French <stfrench@microsoft.com>
parent 7257bcf3

fs/smb/client/cifsglob.h

+0 −1
Original line number Diff line number Diff line
@@ -994,7 +994,6 @@ release_iface(struct kref *ref) 
	struct cifs_server_iface *iface = container_of(ref,

						       struct cifs_server_iface,

						       refcount);

	list_del_init(&iface->iface_head);

	kfree(iface);

}

fs/smb/client/smb2ops.c

+17 −10
Original line number Diff line number Diff line
@@ -595,16 +595,12 @@ parse_server_interfaces(struct network_interface_info_ioctl_rsp *buf, 
	}



	/*

	 * Go through iface_list and do kref_put to remove

	 * any unused ifaces. ifaces in use will be removed

	 * when the last user calls a kref_put on it

	 * Go through iface_list and mark them as inactive

	 */

	list_for_each_entry_safe(iface, niface, &ses->iface_list,

				 iface_head) {

				 iface_head)

		iface->is_active = 0;

		kref_put(&iface->refcount, release_iface);

		ses->iface_count--;

	}



	spin_unlock(&ses->iface_lock);



	/*
@@ -678,10 +674,7 @@ parse_server_interfaces(struct network_interface_info_ioctl_rsp *buf, 
					 iface_head) {

			ret = iface_cmp(iface, &tmp_iface);

			if (!ret) {

				/* just get a ref so that it doesn't get picked/freed */

				iface->is_active = 1;

				kref_get(&iface->refcount);

				ses->iface_count++;

				spin_unlock(&ses->iface_lock);

				goto next_iface;

			} else if (ret < 0) {
@@ -748,6 +741,20 @@ parse_server_interfaces(struct network_interface_info_ioctl_rsp *buf, 
	}



out:

	/*

	 * Go through the list again and put the inactive entries

	 */

	spin_lock(&ses->iface_lock);

	list_for_each_entry_safe(iface, niface, &ses->iface_list,

				 iface_head) {

		if (!iface->is_active) {

			list_del(&iface->iface_head);

			kref_put(&iface->refcount, release_iface);

			ses->iface_count--;

		}

	}

	spin_unlock(&ses->iface_lock);



	return rc;

}