Commit 037ddbcc authored by Shyam Prasad N's avatar Shyam Prasad N Committed by Steve French
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cifs: Corrections to lock ordering notes 



There were a couple of discrepencies in lock ordering for the locks
that were specified in the lock ordering notes. Did an analysis
of the current codebase (using LLM) and found two pairs whose ordering
in these notes were wrong. It also found one lock that was recently
removed, and a few locks that weren't documented here before.

Signed-off-by: default avatarShyam Prasad N <sprasad@microsoft.com>
Signed-off-by: default avatarSteve French <stfrench@microsoft.com>
parent 2c1238a7

fs/smb/client/cifsglob.h

+11 −4
Original line number Diff line number Diff line
@@ -1945,6 +1945,8 @@ require use of the stronger protocol */ 
 */



/****************************************************************************

 * LOCK ORDERING NOTES:

 ****************************************************************************

 * Here are all the locks (spinlock, mutex, semaphore) in cifs.ko, arranged according

 * to the locking order. i.e. if two locks are to be held together, the lock that

 * appears higher in this list needs to be taken before the other.
@@ -1973,18 +1975,21 @@ require use of the stronger protocol */ 
 * =====================================================================================

 * Lock				Protects			Initialization fn

 * =====================================================================================

 * cifs_mount_mutex		mount/unmount operations

 * vol_list_lock

 * vol_info->ctx_lock		vol_info->ctx

 * cifs_sb_info->tlink_tree_lock	cifs_sb_info->tlink_tree	cifs_setup_cifs_sb

 * TCP_Server_Info->		TCP_Server_Info			cifs_get_tcp_session

 * reconnect_mutex

 * TCP_Server_Info->srv_mutex	TCP_Server_Info			cifs_get_tcp_session

 * cifs_ses->session_mutex	cifs_ses			sesInfoAlloc

 * TCP_Server_Info->srv_mutex	TCP_Server_Info			cifs_get_tcp_session

 * cifs_tcp_ses_lock		cifs_tcp_ses_list		sesInfoAlloc

 * cifs_tcon->open_file_lock	cifs_tcon->openFileList		tconInfoAlloc

 *				cifs_tcon->pending_opens

 * cifs_tcon->stat_lock		cifs_tcon->bytes_read		tconInfoAlloc

 *				cifs_tcon->bytes_written

 * cifs_tcp_ses_lock		cifs_tcp_ses_list		sesInfoAlloc

 * cifs_tcon->fscache_lock	cifs_tcon->fscache		tconInfoAlloc

 * cifs_tcon->sb_list_lock	cifs_tcon->cifs_sb_list		tconInfoAlloc

 * GlobalMid_Lock		GlobalMaxActiveXid		init_cifs

 *				GlobalCurrentXid

 *				GlobalTotalActiveXid
@@ -2007,6 +2012,8 @@ require use of the stronger protocol */ 
 *				->chans_in_reconnect

 * cifs_tcon->tc_lock		(anything that is not protected by another lock and can change)

 *								tcon_info_alloc

 * cifs_swnreg_idr_mutex	cifs_swnreg_idr			cifs_swn.c

 *				(witness service registration, accesses tcon fields under tc_lock)

 * inode->i_rwsem, taken by fs/netfs/locking.c e.g. should be taken before cifsInodeInfo locks

 * cifsInodeInfo->open_file_lock	cifsInodeInfo->openFileList	cifs_alloc_inode

 * cifsInodeInfo->writers_lock	cifsInodeInfo->writers		cifsInodeInfo_alloc
@@ -2014,12 +2021,12 @@ require use of the stronger protocol */ 
 *				->can_cache_brlcks

 * cifsInodeInfo->deferred_lock	cifsInodeInfo->deferred_closes	cifsInodeInfo_alloc

 * cached_fids->cfid_list_lock	cifs_tcon->cfids->entries	init_cached_dirs

 * cached_fid->fid_lock		(anything that is not protected by another lock and can change)

 *								init_cached_dir

 * cached_fid->dirents.de_mutex	cached_fid->dirents		alloc_cached_dir

 * cifsFileInfo->fh_mutex	cifsFileInfo			cifs_new_fileinfo

 * cifsFileInfo->file_info_lock	cifsFileInfo->count		cifs_new_fileinfo

 *				->invalidHandle			initiate_cifs_search

 *				->oplock_break_cancelled

 * smbdirect_mr->mutex		RDMA memory region management	(SMBDirect only)

 * mid_q_entry->mid_lock	mid_q_entry->callback           alloc_mid

 *								smb2_mid_entry_alloc

 *				(Any fields of mid_q_entry that will need protection)