Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759900AbXI1G3c (ORCPT ); Fri, 28 Sep 2007 02:29:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756596AbXI1G3Z (ORCPT ); Fri, 28 Sep 2007 02:29:25 -0400 Received: from mx10.go2.pl ([193.17.41.74]:37945 "EHLO poczta.o2.pl" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1756120AbXI1G3X (ORCPT ); Fri, 28 Sep 2007 02:29:23 -0400 Date: Fri, 28 Sep 2007 08:31:44 +0200 From: Jarek Poplawski To: Nadia.Derbey@bull.net Cc: akpm@linux-foundation.org, adobriyan@sw.ru, linux-kernel@vger.kernel.org Subject: Re: [PATCH -mm1 1/2] fixing idr_find() locking Message-ID: <20070928063144.GB1767@ff.dom.local> References: <20070927143354.663489000@bull.net> <20070927143458.674281000@bull.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070927143458.674281000@bull.net> User-Agent: Mutt/1.4.2.2i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 25474 Lines: 790 On Thu, Sep 27, 2007 at 04:33:55PM +0200, Nadia.Derbey@bull.net wrote: > [PATCH 01/02] > > > This is a patch that fixes the way idr_find() used to be called in ipc_lock(): > in all the paths that don't imply an update of the ipcs idr, it was called > without the idr tree being locked. > > The changes are: > . in ipc_ids, the mutex has been changed into a reader/writer semaphore. > . ipc_lock() now takes the mutex as a reader during the idr_find(). > . a new routine ipc_lock_down() has been defined: it doesn't take the > mutex, assuming that it is being held by the caller. This is the routine > that is now called in all the update paths. > > > Signed-off-by: Nadia Derbey Acked-by: Jarek Poplawski PS: there is one big mistake around To/Cc ordering, so I doubt Andrew will ever sign this... > > --- > > This patch applies on top of the 2.6.23-rc6-mm1 > > > ipc/msg.c | 41 ++++++++++++++++++++++---------- > ipc/sem.c | 44 +++++++++++++++++++++++----------- > ipc/shm.c | 77 +++++++++++++++++++++++++++++++++++++++--------------------- > ipc/util.c | 78 ++++++++++++++++++++++++++++++++++++++++++++++++------------- > ipc/util.h | 28 ++++++++++++++++++++- > 5 files changed, 198 insertions(+), 70 deletions(-) > > Index: linux-2.6.23-rc6-mm1/ipc/util.h > =================================================================== > --- linux-2.6.23-rc6-mm1.orig/ipc/util.h 2007-09-25 12:38:17.000000000 +0200 > +++ linux-2.6.23-rc6-mm1/ipc/util.h 2007-09-27 10:13:18.000000000 +0200 > @@ -32,7 +32,7 @@ struct ipc_ids { > int in_use; > unsigned short seq; > unsigned short seq_max; > - struct mutex mutex; > + struct rw_semaphore rw_mutex; > struct idr ipcs_idr; > }; > > @@ -81,8 +81,10 @@ void __init ipc_init_proc_interface(cons > > #define ipcid_to_idx(id) ((id) % SEQ_MULTIPLIER) > > -/* must be called with ids->mutex acquired.*/ > +/* must be called with ids->rw_mutex acquired for writing */ > int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int); > + > +/* must be called with ids->rw_mutex acquired for reading */ > int ipc_get_maxid(struct ipc_ids *); > > /* must be called with both locks acquired. */ > @@ -107,6 +109,11 @@ void* ipc_rcu_alloc(int size); > void ipc_rcu_getref(void *ptr); > void ipc_rcu_putref(void *ptr); > > +/* > + * ipc_lock_down: called with rw_mutex held > + * ipc_lock: called without that lock held > + */ > +struct kern_ipc_perm *ipc_lock_down(struct ipc_ids *, int); > struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int); > > void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out); > @@ -155,6 +162,23 @@ static inline void ipc_unlock(struct ker > rcu_read_unlock(); > } > > +static inline struct kern_ipc_perm *ipc_lock_check_down(struct ipc_ids *ids, > + int id) > +{ > + struct kern_ipc_perm *out; > + > + out = ipc_lock_down(ids, id); > + if (IS_ERR(out)) > + return out; > + > + if (ipc_checkid(ids, out, id)) { > + ipc_unlock(out); > + return ERR_PTR(-EIDRM); > + } > + > + return out; > +} > + > static inline struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids, > int id) > { > Index: linux-2.6.23-rc6-mm1/ipc/util.c > =================================================================== > --- linux-2.6.23-rc6-mm1.orig/ipc/util.c 2007-09-21 10:32:03.000000000 +0200 > +++ linux-2.6.23-rc6-mm1/ipc/util.c 2007-09-27 14:37:55.000000000 +0200 > @@ -32,6 +32,7 @@ > #include > #include > #include > +#include > > #include > > @@ -136,7 +137,7 @@ __initcall(ipc_init); > > void ipc_init_ids(struct ipc_ids *ids) > { > - mutex_init(&ids->mutex); > + init_rwsem(&ids->rw_mutex); > > ids->in_use = 0; > ids->seq = 0; > @@ -191,7 +192,7 @@ void __init ipc_init_proc_interface(cons > * @ids: Identifier set > * @key: The key to find > * > - * Requires ipc_ids.mutex locked. > + * Requires ipc_ids.rw_mutex locked. > * Returns the LOCKED pointer to the ipc structure if found or NULL > * if not. > * If key is found ipc points to the owning ipc structure > @@ -225,7 +226,7 @@ static struct kern_ipc_perm *ipc_findkey > * ipc_get_maxid - get the last assigned id > * @ids: IPC identifier set > * > - * Called with ipc_ids.mutex held. > + * Called with ipc_ids.rw_mutex held. > */ > > int ipc_get_maxid(struct ipc_ids *ids) > @@ -263,7 +264,7 @@ int ipc_get_maxid(struct ipc_ids *ids) > * is returned. The 'new' entry is returned in a locked state on success. > * On failure the entry is not locked and -1 is returned. > * > - * Called with ipc_ids.mutex held. > + * Called with ipc_ids.rw_mutex held as a writer. > */ > > int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size) > @@ -316,9 +317,9 @@ int ipcget_new(struct ipc_namespace *ns, > if (!err) > return -ENOMEM; > > - mutex_lock(&ids->mutex); > + down_write(&ids->rw_mutex); > err = ops->getnew(ns, params); > - mutex_unlock(&ids->mutex); > + up_write(&ids->rw_mutex); > > return err; > } > @@ -335,7 +336,7 @@ int ipcget_new(struct ipc_namespace *ns, > * > * On success, the IPC id is returned. > * > - * It is called with ipc_ids.mutex and ipcp->lock held. > + * It is called with ipc_ids.rw_mutex and ipcp->lock held. > */ > static int ipc_check_perms(struct kern_ipc_perm *ipcp, struct ipc_ops *ops, > struct ipc_params *params) > @@ -376,7 +377,11 @@ int ipcget_public(struct ipc_namespace * > > err = idr_pre_get(&ids->ipcs_idr, GFP_KERNEL); > > - mutex_lock(&ids->mutex); > + /* > + * Take the lock as a writer since we are potentially going to add > + * a new entry + read locks are not "upgradable" > + */ > + down_write(&ids->rw_mutex); > ipcp = ipc_findkey(ids, params->key); > if (ipcp == NULL) { > /* key not used */ > @@ -404,7 +409,7 @@ int ipcget_public(struct ipc_namespace * > } > ipc_unlock(ipcp); > } > - mutex_unlock(&ids->mutex); > + up_write(&ids->rw_mutex); > > return err; > } > @@ -415,8 +420,8 @@ int ipcget_public(struct ipc_namespace * > * @ids: IPC identifier set > * @ipcp: ipc perm structure containing the identifier to remove > * > - * ipc_ids.mutex and the spinlock for this ID are held before this > - * function is called, and remain locked on the exit. > + * ipc_ids.rw_mutex (as a writer) and the spinlock for this ID are held > + * before this function is called, and remain locked on the exit. > */ > > void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp) > @@ -680,15 +685,17 @@ void ipc64_perm_to_ipc_perm (struct ipc6 > } > > /** > - * ipc_lock - Lock an ipc structure > + * ipc_lock - Lock an ipc structure without rw_mutex held > * @ids: IPC identifier set > * @id: ipc id to look for > * > * Look for an id in the ipc ids idr and lock the associated ipc object. > * > - * ipc_ids.mutex is not necessarily held before this function is called, > - * that's why we enter a RCU read section. > * The ipc object is locked on exit. > + * > + * This is the routine that should be called when the rw_mutex is not already > + * held, i.e. idr tree not protected: it protects the idr tree in read mode > + * during the idr_find(). > */ > > struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id) > @@ -696,13 +703,18 @@ struct kern_ipc_perm *ipc_lock(struct ip > struct kern_ipc_perm *out; > int lid = ipcid_to_idx(id); > > + down_read(&ids->rw_mutex); > + > rcu_read_lock(); > out = idr_find(&ids->ipcs_idr, lid); > if (out == NULL) { > rcu_read_unlock(); > + up_read(&ids->rw_mutex); > return ERR_PTR(-EINVAL); > } > > + up_read(&ids->rw_mutex); > + > spin_lock(&out->lock); > > /* ipc_rmid() may have already freed the ID while ipc_lock > @@ -717,6 +729,40 @@ struct kern_ipc_perm *ipc_lock(struct ip > return out; > } > > +/** > + * ipc_lock_down - Lock an ipc structure with rw_sem held > + * @ids: IPC identifier set > + * @id: ipc id to look for > + * > + * Look for an id in the ipc ids idr and lock the associated ipc object. > + * > + * The ipc object is locked on exit. > + * > + * This is the routine that should be called when the rw_mutex is already > + * held, i.e. idr tree protected. > + */ > + > +struct kern_ipc_perm *ipc_lock_down(struct ipc_ids *ids, int id) > +{ > + struct kern_ipc_perm *out; > + int lid = ipcid_to_idx(id); > + > + rcu_read_lock(); > + out = idr_find(&ids->ipcs_idr, lid); > + if (out == NULL) { > + rcu_read_unlock(); > + return ERR_PTR(-EINVAL); > + } > + > + spin_lock(&out->lock); > + > + /* > + * No need to verify that the structure is still valid since the > + * rw_mutex is held. > + */ > + return out; > +} > + > #ifdef __ARCH_WANT_IPC_PARSE_VERSION > > > @@ -808,7 +854,7 @@ static void *sysvipc_proc_start(struct s > * Take the lock - this will be released by the corresponding > * call to stop(). > */ > - mutex_lock(&ids->mutex); > + down_read(&ids->rw_mutex); > > /* pos < 0 is invalid */ > if (*pos < 0) > @@ -835,7 +881,7 @@ static void sysvipc_proc_stop(struct seq > > ids = iter->ns->ids[iface->ids]; > /* Release the lock we took in start() */ > - mutex_unlock(&ids->mutex); > + up_read(&ids->rw_mutex); > } > > static int sysvipc_proc_show(struct seq_file *s, void *it) > Index: linux-2.6.23-rc6-mm1/ipc/msg.c > =================================================================== > --- linux-2.6.23-rc6-mm1.orig/ipc/msg.c 2007-09-21 10:33:08.000000000 +0200 > +++ linux-2.6.23-rc6-mm1/ipc/msg.c 2007-09-27 10:34:25.000000000 +0200 > @@ -34,7 +34,7 @@ > #include > #include > #include > -#include > +#include > #include > > #include > @@ -110,7 +110,7 @@ void msg_exit_ns(struct ipc_namespace *n > int next_id; > int total, in_use; > > - mutex_lock(&msg_ids(ns).mutex); > + down_write(&msg_ids(ns).rw_mutex); > > in_use = msg_ids(ns).in_use; > > @@ -122,7 +122,8 @@ void msg_exit_ns(struct ipc_namespace *n > freeque(ns, msq); > total++; > } > - mutex_unlock(&msg_ids(ns).mutex); > + > + up_write(&msg_ids(ns).rw_mutex); > > kfree(ns->ids[IPC_MSG_IDS]); > ns->ids[IPC_MSG_IDS] = NULL; > @@ -136,6 +137,22 @@ void __init msg_init(void) > IPC_MSG_IDS, sysvipc_msg_proc_show); > } > > +/* > + * This routine is called in the paths where the rw_mutex is held to protect > + * access to the idr tree. > + */ > +static inline struct msg_queue *msg_lock_check_down(struct ipc_namespace *ns, > + int id) > +{ > + struct kern_ipc_perm *ipcp = ipc_lock_check_down(&msg_ids(ns), id); > + > + return container_of(ipcp, struct msg_queue, q_perm); > +} > + > +/* > + * msg_lock_(check_) routines are called in the paths where the rw_mutex > + * is not held. > + */ > static inline struct msg_queue *msg_lock(struct ipc_namespace *ns, int id) > { > struct kern_ipc_perm *ipcp = ipc_lock(&msg_ids(ns), id); > @@ -161,7 +178,7 @@ static inline void msg_rmid(struct ipc_n > * @ns: namespace > * @params: ptr to the structure that contains the key and msgflg > * > - * Called with msg_ids.mutex held > + * Called with msg_ids.rw_mutex held (writer) > */ > static int newque(struct ipc_namespace *ns, struct ipc_params *params) > { > @@ -260,8 +277,8 @@ static void expunge_all(struct msg_queue > * removes the message queue from message queue ID IDR, and cleans up all the > * messages associated with this queue. > * > - * msg_ids.mutex and the spinlock for this message queue are held > - * before freeque() is called. msg_ids.mutex remains locked on exit. > + * msg_ids.rw_mutex (writer) and the spinlock for this message queue are held > + * before freeque() is called. msg_ids.rw_mutex remains locked on exit. > */ > static void freeque(struct ipc_namespace *ns, struct msg_queue *msq) > { > @@ -286,7 +303,7 @@ static void freeque(struct ipc_namespace > } > > /* > - * Called with msg_ids.mutex and ipcp locked. > + * Called with msg_ids.rw_mutex and ipcp locked. > */ > static inline int msg_security(struct kern_ipc_perm *ipcp, int msgflg) > { > @@ -444,7 +461,7 @@ asmlinkage long sys_msgctl(int msqid, in > msginfo.msgmnb = ns->msg_ctlmnb; > msginfo.msgssz = MSGSSZ; > msginfo.msgseg = MSGSEG; > - mutex_lock(&msg_ids(ns).mutex); > + down_read(&msg_ids(ns).rw_mutex); > if (cmd == MSG_INFO) { > msginfo.msgpool = msg_ids(ns).in_use; > msginfo.msgmap = atomic_read(&msg_hdrs); > @@ -455,7 +472,7 @@ asmlinkage long sys_msgctl(int msqid, in > msginfo.msgtql = MSGTQL; > } > max_id = ipc_get_maxid(&msg_ids(ns)); > - mutex_unlock(&msg_ids(ns).mutex); > + up_read(&msg_ids(ns).rw_mutex); > if (copy_to_user(buf, &msginfo, sizeof(struct msginfo))) > return -EFAULT; > return (max_id < 0) ? 0 : max_id; > @@ -516,8 +533,8 @@ asmlinkage long sys_msgctl(int msqid, in > return -EINVAL; > } > > - mutex_lock(&msg_ids(ns).mutex); > - msq = msg_lock_check(ns, msqid); > + down_write(&msg_ids(ns).rw_mutex); > + msq = msg_lock_check_down(ns, msqid); > if (IS_ERR(msq)) { > err = PTR_ERR(msq); > goto out_up; > @@ -576,7 +593,7 @@ asmlinkage long sys_msgctl(int msqid, in > } > err = 0; > out_up: > - mutex_unlock(&msg_ids(ns).mutex); > + up_write(&msg_ids(ns).rw_mutex); > return err; > out_unlock_up: > msg_unlock(msq); > Index: linux-2.6.23-rc6-mm1/ipc/sem.c > =================================================================== > --- linux-2.6.23-rc6-mm1.orig/ipc/sem.c 2007-09-21 10:33:50.000000000 +0200 > +++ linux-2.6.23-rc6-mm1/ipc/sem.c 2007-09-27 10:35:40.000000000 +0200 > @@ -80,7 +80,7 @@ > #include > #include > #include > -#include > +#include > #include > > #include > @@ -148,7 +148,7 @@ void sem_exit_ns(struct ipc_namespace *n > int next_id; > int total, in_use; > > - mutex_lock(&sem_ids(ns).mutex); > + down_write(&sem_ids(ns).rw_mutex); > > in_use = sem_ids(ns).in_use; > > @@ -160,7 +160,7 @@ void sem_exit_ns(struct ipc_namespace *n > freeary(ns, sma); > total++; > } > - mutex_unlock(&sem_ids(ns).mutex); > + up_write(&sem_ids(ns).rw_mutex); > > kfree(ns->ids[IPC_SEM_IDS]); > ns->ids[IPC_SEM_IDS] = NULL; > @@ -174,6 +174,22 @@ void __init sem_init (void) > IPC_SEM_IDS, sysvipc_sem_proc_show); > } > > +/* > + * This routine is called in the paths where the rw_mutex is held to protect > + * access to the idr tree. > + */ > +static inline struct sem_array *sem_lock_check_down(struct ipc_namespace *ns, > + int id) > +{ > + struct kern_ipc_perm *ipcp = ipc_lock_check_down(&sem_ids(ns), id); > + > + return container_of(ipcp, struct sem_array, sem_perm); > +} > + > +/* > + * sem_lock_(check_) routines are called in the paths where the rw_mutex > + * is not held. > + */ > static inline struct sem_array *sem_lock(struct ipc_namespace *ns, int id) > { > struct kern_ipc_perm *ipcp = ipc_lock(&sem_ids(ns), id); > @@ -233,7 +249,7 @@ static inline void sem_rmid(struct ipc_n > * @ns: namespace > * @params: ptr to the structure that contains key, semflg and nsems > * > - * Called with sem_ids.mutex held > + * Called with sem_ids.rw_mutex held (as a writer) > */ > > static int newary(struct ipc_namespace *ns, struct ipc_params *params) > @@ -290,7 +306,7 @@ static int newary(struct ipc_namespace * > > > /* > - * Called with sem_ids.mutex and ipcp locked. > + * Called with sem_ids.rw_mutex and ipcp locked. > */ > static inline int sem_security(struct kern_ipc_perm *ipcp, int semflg) > { > @@ -301,7 +317,7 @@ static inline int sem_security(struct ke > } > > /* > - * Called with sem_ids.mutex and ipcp locked. > + * Called with sem_ids.rw_mutex and ipcp locked. > */ > static inline int sem_more_checks(struct kern_ipc_perm *ipcp, > struct ipc_params *params) > @@ -528,9 +544,9 @@ static int count_semzcnt (struct sem_arr > return semzcnt; > } > > -/* Free a semaphore set. freeary() is called with sem_ids.mutex locked and > - * the spinlock for this semaphore set hold. sem_ids.mutex remains locked > - * on exit. > +/* Free a semaphore set. freeary() is called with sem_ids.rw_mutex locked > + * as a writer and the spinlock for this semaphore set hold. sem_ids.rw_mutex > + * remains locked on exit. > */ > static void freeary(struct ipc_namespace *ns, struct sem_array *sma) > { > @@ -615,7 +631,7 @@ static int semctl_nolock(struct ipc_name > seminfo.semmnu = SEMMNU; > seminfo.semmap = SEMMAP; > seminfo.semume = SEMUME; > - mutex_lock(&sem_ids(ns).mutex); > + down_read(&sem_ids(ns).rw_mutex); > if (cmd == SEM_INFO) { > seminfo.semusz = sem_ids(ns).in_use; > seminfo.semaem = ns->used_sems; > @@ -624,7 +640,7 @@ static int semctl_nolock(struct ipc_name > seminfo.semaem = SEMAEM; > } > max_id = ipc_get_maxid(&sem_ids(ns)); > - mutex_unlock(&sem_ids(ns).mutex); > + up_read(&sem_ids(ns).rw_mutex); > if (copy_to_user (arg.__buf, &seminfo, sizeof(struct seminfo))) > return -EFAULT; > return (max_id < 0) ? 0: max_id; > @@ -895,7 +911,7 @@ static int semctl_down(struct ipc_namesp > if(copy_semid_from_user (&setbuf, arg.buf, version)) > return -EFAULT; > } > - sma = sem_lock_check(ns, semid); > + sma = sem_lock_check_down(ns, semid); > if (IS_ERR(sma)) > return PTR_ERR(sma); > > @@ -976,9 +992,9 @@ asmlinkage long sys_semctl (int semid, i > return err; > case IPC_RMID: > case IPC_SET: > - mutex_lock(&sem_ids(ns).mutex); > + down_write(&sem_ids(ns).rw_mutex); > err = semctl_down(ns,semid,semnum,cmd,version,arg); > - mutex_unlock(&sem_ids(ns).mutex); > + up_write(&sem_ids(ns).rw_mutex); > return err; > default: > return -EINVAL; > Index: linux-2.6.23-rc6-mm1/ipc/shm.c > =================================================================== > --- linux-2.6.23-rc6-mm1.orig/ipc/shm.c 2007-09-21 10:34:25.000000000 +0200 > +++ linux-2.6.23-rc6-mm1/ipc/shm.c 2007-09-27 10:30:30.000000000 +0200 > @@ -35,7 +35,7 @@ > #include > #include > #include > -#include > +#include > #include > #include > > @@ -83,8 +83,8 @@ static void __shm_init_ns(struct ipc_nam > } > > /* > - * Called with shm_ids.mutex and the shp structure locked. > - * Only shm_ids.mutex remains locked on exit. > + * Called with shm_ids.rw_mutex (writer) and the shp structure locked. > + * Only shm_ids.rw_mutex remains locked on exit. > */ > static void do_shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *shp) > { > @@ -115,7 +115,7 @@ void shm_exit_ns(struct ipc_namespace *n > int next_id; > int total, in_use; > > - mutex_lock(&shm_ids(ns).mutex); > + down_write(&shm_ids(ns).rw_mutex); > > in_use = shm_ids(ns).in_use; > > @@ -127,7 +127,7 @@ void shm_exit_ns(struct ipc_namespace *n > do_shm_rmid(ns, shp); > total++; > } > - mutex_unlock(&shm_ids(ns).mutex); > + up_write(&shm_ids(ns).rw_mutex); > > kfree(ns->ids[IPC_SHM_IDS]); > ns->ids[IPC_SHM_IDS] = NULL; > @@ -141,6 +141,31 @@ void __init shm_init (void) > IPC_SHM_IDS, sysvipc_shm_proc_show); > } > > +/* > + * shm_lock_(check_)down routines are called in the paths where the rw_mutex > + * is held to protect access to the idr tree. > + */ > +static inline struct shmid_kernel *shm_lock_down(struct ipc_namespace *ns, > + int id) > +{ > + struct kern_ipc_perm *ipcp = ipc_lock_down(&shm_ids(ns), id); > + > + return container_of(ipcp, struct shmid_kernel, shm_perm); > +} > + > +static inline struct shmid_kernel *shm_lock_check_down( > + struct ipc_namespace *ns, > + int id) > +{ > + struct kern_ipc_perm *ipcp = ipc_lock_check_down(&shm_ids(ns), id); > + > + return container_of(ipcp, struct shmid_kernel, shm_perm); > +} > + > +/* > + * shm_lock_(check_) routines are called in the paths where the rw_mutex > + * is not held. > + */ > static inline struct shmid_kernel *shm_lock(struct ipc_namespace *ns, int id) > { > struct kern_ipc_perm *ipcp = ipc_lock(&shm_ids(ns), id); > @@ -189,7 +214,7 @@ static void shm_open(struct vm_area_stru > * @ns: namespace > * @shp: struct to free > * > - * It has to be called with shp and shm_ids.mutex locked, > + * It has to be called with shp and shm_ids.rw_mutex (writer) locked, > * but returns with shp unlocked and freed. > */ > static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp) > @@ -220,9 +245,9 @@ static void shm_close(struct vm_area_str > struct shmid_kernel *shp; > struct ipc_namespace *ns = sfd->ns; > > - mutex_lock(&shm_ids(ns).mutex); > + down_write(&shm_ids(ns).rw_mutex); > /* remove from the list of attaches of the shm segment */ > - shp = shm_lock(ns, sfd->id); > + shp = shm_lock_down(ns, sfd->id); > BUG_ON(IS_ERR(shp)); > shp->shm_lprid = task_tgid_vnr(current); > shp->shm_dtim = get_seconds(); > @@ -232,7 +257,7 @@ static void shm_close(struct vm_area_str > shm_destroy(ns, shp); > else > shm_unlock(shp); > - mutex_unlock(&shm_ids(ns).mutex); > + up_write(&shm_ids(ns).rw_mutex); > } > > static int shm_fault(struct vm_area_struct *vma, struct vm_fault *vmf) > @@ -353,7 +378,7 @@ static struct vm_operations_struct shm_v > * @ns: namespace > * @params: ptr to the structure that contains key, size and shmflg > * > - * Called with shm_ids.mutex held > + * Called with shm_ids.rw_mutex held as a writer. > */ > > static int newseg(struct ipc_namespace *ns, struct ipc_params *params) > @@ -442,7 +467,7 @@ no_file: > } > > /* > - * Called with shm_ids.mutex and ipcp locked. > + * Called with shm_ids.rw_mutex and ipcp locked. > */ > static inline int shm_security(struct kern_ipc_perm *ipcp, int shmflg) > { > @@ -453,7 +478,7 @@ static inline int shm_security(struct ke > } > > /* > - * Called with shm_ids.mutex and ipcp locked. > + * Called with shm_ids.rw_mutex and ipcp locked. > */ > static inline int shm_more_checks(struct kern_ipc_perm *ipcp, > struct ipc_params *params) > @@ -578,7 +603,7 @@ static inline unsigned long copy_shminfo > } > > /* > - * Called with shm_ids.mutex held > + * Called with shm_ids.rw_mutex held as a reader > */ > static void shm_get_stat(struct ipc_namespace *ns, unsigned long *rss, > unsigned long *swp) > @@ -649,9 +674,9 @@ asmlinkage long sys_shmctl (int shmid, i > if(copy_shminfo_to_user (buf, &shminfo, version)) > return -EFAULT; > > - mutex_lock(&shm_ids(ns).mutex); > + down_read(&shm_ids(ns).rw_mutex); > err = ipc_get_maxid(&shm_ids(ns)); > - mutex_unlock(&shm_ids(ns).mutex); > + up_read(&shm_ids(ns).rw_mutex); > > if(err<0) > err = 0; > @@ -666,14 +691,14 @@ asmlinkage long sys_shmctl (int shmid, i > return err; > > memset(&shm_info,0,sizeof(shm_info)); > - mutex_lock(&shm_ids(ns).mutex); > + down_read(&shm_ids(ns).rw_mutex); > shm_info.used_ids = shm_ids(ns).in_use; > shm_get_stat (ns, &shm_info.shm_rss, &shm_info.shm_swp); > shm_info.shm_tot = ns->shm_tot; > shm_info.swap_attempts = 0; > shm_info.swap_successes = 0; > err = ipc_get_maxid(&shm_ids(ns)); > - mutex_unlock(&shm_ids(ns).mutex); > + up_read(&shm_ids(ns).rw_mutex); > if(copy_to_user (buf, &shm_info, sizeof(shm_info))) { > err = -EFAULT; > goto out; > @@ -786,8 +811,8 @@ asmlinkage long sys_shmctl (int shmid, i > * Instead we set a destroyed flag, and then blow > * the name away when the usage hits zero. > */ > - mutex_lock(&shm_ids(ns).mutex); > - shp = shm_lock_check(ns, shmid); > + down_write(&shm_ids(ns).rw_mutex); > + shp = shm_lock_check_down(ns, shmid); > if (IS_ERR(shp)) { > err = PTR_ERR(shp); > goto out_up; > @@ -809,7 +834,7 @@ asmlinkage long sys_shmctl (int shmid, i > goto out_unlock_up; > > do_shm_rmid(ns, shp); > - mutex_unlock(&shm_ids(ns).mutex); > + up_write(&shm_ids(ns).rw_mutex); > goto out; > } > > @@ -824,8 +849,8 @@ asmlinkage long sys_shmctl (int shmid, i > err = -EFAULT; > goto out; > } > - mutex_lock(&shm_ids(ns).mutex); > - shp = shm_lock_check(ns, shmid); > + down_write(&shm_ids(ns).rw_mutex); > + shp = shm_lock_check_down(ns, shmid); > if (IS_ERR(shp)) { > err = PTR_ERR(shp); > goto out_up; > @@ -864,7 +889,7 @@ asmlinkage long sys_shmctl (int shmid, i > out_unlock_up: > shm_unlock(shp); > out_up: > - mutex_unlock(&shm_ids(ns).mutex); > + up_write(&shm_ids(ns).rw_mutex); > goto out; > out_unlock: > shm_unlock(shp); > @@ -1000,8 +1025,8 @@ invalid: > fput(file); > > out_nattch: > - mutex_lock(&shm_ids(ns).mutex); > - shp = shm_lock(ns, shmid); > + down_write(&shm_ids(ns).rw_mutex); > + shp = shm_lock_down(ns, shmid); > BUG_ON(IS_ERR(shp)); > shp->shm_nattch--; > if(shp->shm_nattch == 0 && > @@ -1009,7 +1034,7 @@ out_nattch: > shm_destroy(ns, shp); > else > shm_unlock(shp); > - mutex_unlock(&shm_ids(ns).mutex); > + up_write(&shm_ids(ns).rw_mutex); > > out: > return err; > > -- > - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/