6.1-stable review patch. If anyone has any objections, please let me know.
------------------
From: Shyam Prasad N sprasad@microsoft.com
commit 09eeb0723f219fbd96d8865bf9b935e03ee2ec22 upstream.
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: aa45dadd34e4 ("cifs: change iface_list from array to sorted linked list") Cc: stable@vger.kernel.org Signed-off-by: Shyam Prasad N sprasad@microsoft.com Signed-off-by: Steve French stfrench@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/smb/client/cifsglob.h | 1 - fs/smb/client/smb2ops.c | 27 +++++++++++++++++---------- 2 files changed, 17 insertions(+), 11 deletions(-)
--- a/fs/smb/client/cifsglob.h +++ b/fs/smb/client/cifsglob.h @@ -972,7 +972,6 @@ 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); }
--- a/fs/smb/client/smb2ops.c +++ b/fs/smb/client/smb2ops.c @@ -588,16 +588,12 @@ parse_server_interfaces(struct network_i }
/* - * 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);
/* @@ -672,10 +668,7 @@ parse_server_interfaces(struct network_i 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) { @@ -742,6 +735,20 @@ next_iface: }
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; }