From: Davidlohr Bueso <dave@xxxxxxxxxxxx>
Subject: sysvipc: unteach ids->next_id for !CHECKPOINT_RESTORE
Patch series "sysvipc: ipc-key management improvements".
Here are a few improvements I spotted while eyeballing Guillaume's
rhashtable implementation for ipc keys. The first and fourth patches are
the interesting ones, the middle two are trivial.
This patch (of 4):
The next_id object-allocation functionality was introduced in
03f595668017f ("ipc: add sysctl to specify desired next object id").
Given that these new entries are _only_ exported under the
CONFIG_CHECKPOINT_RESTORE option, there is no point for the common case to
even know about ->next_id. As such rewrite ipc_buildid() such that it can
do away with the field as well as unnecessary branches when adding a new
identifier. The end result also better differentiates both cases, so the
code ends up being cleaner; albeit the small duplications regarding the
default case.
[akpm@xxxxxxxxxxxxxxxxxxxx: coding-style fixes]
Link: http://lkml.kernel.org/r/20170831172049.14576-2-dave@xxxxxxxxxxxx
Signed-off-by: Davidlohr Bueso <dbueso@xxxxxxx>
Cc: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/ipc_namespace.h | 2 +
ipc/util.c | 60 ++++++++++++++++++++++++--------
ipc/util.h | 5 --
3 files changed, 47 insertions(+), 20 deletions(-)
diff -puN include/linux/ipc_namespace.h~sysvipc-unteach-ids-next_id-for-checkpoint_restore include/linux/ipc_namespace.h
--- a/include/linux/ipc_namespace.h~sysvipc-unteach-ids-next_id-for-checkpoint_restore
+++ a/include/linux/ipc_namespace.h
@@ -19,7 +19,9 @@ struct ipc_ids {
bool tables_initialized;
struct rw_semaphore rwsem;
struct idr ipcs_idr;
+#ifdef CONFIG_CHECKPOINT_RESTORE
int next_id;
+#endif
struct rhashtable key_ht;
};
diff -puN ipc/util.c~sysvipc-unteach-ids-next_id-for-checkpoint_restore ipc/util.c
--- a/ipc/util.c~sysvipc-unteach-ids-next_id-for-checkpoint_restore
+++ a/ipc/util.c
@@ -116,13 +116,15 @@ int ipc_init_ids(struct ipc_ids *ids)
int err;
ids->in_use = 0;
ids->seq = 0;
- ids->next_id = -1;
init_rwsem(&ids->rwsem);
err = rhashtable_init(&ids->key_ht, &ipc_kht_params);
if (err)
return err;
idr_init(&ids->ipcs_idr);
ids->tables_initialized = true;
+#ifdef CONFIG_CHECKPOINT_RESTORE
+ ids->next_id = -1;
+#endif
return 0;
}
@@ -216,6 +218,46 @@ int ipc_get_maxid(struct ipc_ids *ids)
return max_id;
}
+#ifdef CONFIG_CHECKPOINT_RESTORE
+/*
+ * Specify desired id for next allocated IPC object.
+ */
+#define ipc_idr_alloc(ids, new) \
+ idr_alloc(&(ids)->ipcs_idr, (new), \
+ (ids)->next_id < 0 ? 0 : ipcid_to_idx((ids)->next_id),\
+ 0, GFP_NOWAIT)
+
+static inline int ipc_buildid(int id, struct ipc_ids *ids,
+ struct kern_ipc_perm *new)
+{
+ if (ids->next_id < 0) { /* default, behave as !CHECKPOINT_RESTORE */
+ new->seq = ids->seq++;
+ if (ids->seq > IPCID_SEQ_MAX)
+ ids->seq = 0;
+ } else {
+ new->seq = ipcid_to_seqx(ids->next_id);
+ ids->next_id = -1;
+ }
+
+ return SEQ_MULTIPLIER * new->seq + id;
+}
+
+#else
+#define ipc_idr_alloc(ids, new) \
+ idr_alloc(&(ids)->ipcs_idr, (new), 0, 0, GFP_NOWAIT)
+
+static inline int ipc_buildid(int id, struct ipc_ids *ids,
+ struct kern_ipc_perm *new)
+{
+ new->seq = ids->seq++;
+ if (ids->seq > IPCID_SEQ_MAX)
+ ids->seq = 0;
+
+ return SEQ_MULTIPLIER * new->seq + id;
+}
+
+#endif /* CONFIG_CHECKPOINT_RESTORE */
+
/**
* ipc_addid - add an ipc identifier
* @ids: ipc identifier set
@@ -234,7 +276,6 @@ int ipc_addid(struct ipc_ids *ids, struc
kuid_t euid;
kgid_t egid;
int id, err;
- int next_id = ids->next_id;
if (size > IPCMNI)
size = IPCMNI;
@@ -254,9 +295,7 @@ int ipc_addid(struct ipc_ids *ids, struc
new->cuid = new->uid = euid;
new->gid = new->cgid = egid;
- id = idr_alloc(&ids->ipcs_idr, new,
- (next_id < 0) ? 0 : ipcid_to_idx(next_id), 0,
- GFP_NOWAIT);
+ id = ipc_idr_alloc(ids, new);
idr_preload_end();
if (id >= 0 && new->key != IPC_PRIVATE) {
@@ -274,17 +313,8 @@ int ipc_addid(struct ipc_ids *ids, struc
}
ids->in_use++;
+ new->id = ipc_buildid(id, ids, new);
- if (next_id < 0) {
- new->seq = ids->seq++;
- if (ids->seq > IPCID_SEQ_MAX)
- ids->seq = 0;
- } else {
- new->seq = ipcid_to_seqx(next_id);
- ids->next_id = -1;
- }
-
- new->id = ipc_buildid(id, new->seq);
return id;
}
diff -puN ipc/util.h~sysvipc-unteach-ids-next_id-for-checkpoint_restore ipc/util.h
--- a/ipc/util.h~sysvipc-unteach-ids-next_id-for-checkpoint_restore
+++ a/ipc/util.h
@@ -146,11 +146,6 @@ extern struct msg_msg *load_msg(const vo
extern struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst);
extern int store_msg(void __user *dest, struct msg_msg *msg, size_t len);
-static inline int ipc_buildid(int id, int seq)
-{
- return SEQ_MULTIPLIER * seq + id;
-}
-
static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int uid)
{
return uid / SEQ_MULTIPLIER != ipcp->seq;
_
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
