genesi/linux-legacy
1
0
Fork 0
mirror of https://github.com/genesi/linux-legacy.git synced 2026-05-20 11:44:14 +00:00
Code Issues Packages Projects Releases Wiki Activity

fix idr_find() locking

Browse Source 
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 <Nadia.Derbey@bull.net>
Acked-by: Jarek Poplawski <jarkao2@o2.pl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Nadia Derbey
2007-10-18 23:40:54 -07:00
committed by Linus Torvalds
parent f4566f0485
commit 3e148c7993
5 changed files with 198 additions and 70 deletions
Download Patch File Download Diff File Expand all files Collapse all files

28
ipc/util.h
View File

@@ -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(const char *path, const char *header,
#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 kern_ipc_perm *perm)
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)
{