Subject: + ipc-semc-remove-code-duplication.patch added to -mm tree
To: manfred@xxxxxxxxxxxxxxxx,davidlohr.bueso@xxxxxx,mtk.manpages@xxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Mon, 19 May 2014 15:46:48 -0700
The patch titled
Subject: ipc/sem.c: remove code duplication
has been added to the -mm tree. Its filename is
ipc-semc-remove-code-duplication.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/ipc-semc-remove-code-duplication.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/ipc-semc-remove-code-duplication.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
Subject: ipc/sem.c: remove code duplication
count_semzcnt and count_semncnt are more of less identical. The patch
creates a single function that either counts the number of tasks waiting
for zero or waiting due to a decrease operation.
Compared to the initial version, the BUG_ONs were removed.
Signed-off-by: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
Cc: Davidlohr Bueso <davidlohr.bueso@xxxxxx>
Cc: Michael Kerrisk <mtk.manpages@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
ipc/sem.c | 107 ++++++++++++++++++++++++----------------------------
1 file changed, 51 insertions(+), 56 deletions(-)
diff -puN ipc/sem.c~ipc-semc-remove-code-duplication ipc/sem.c
--- a/ipc/sem.c~ipc-semc-remove-code-duplication
+++ a/ipc/sem.c
@@ -47,8 +47,7 @@
* Thus: Perfect SMP scaling between independent semaphore arrays.
* If multiple semaphores in one array are used, then cache line
* trashing on the semaphore array spinlock will limit the scaling.
- * - semncnt and semzcnt are calculated on demand in count_semncnt() and
- * count_semzcnt()
+ * - semncnt and semzcnt are calculated on demand in count_semcnt()
* - the task that performs a successful semop() scans the list of all
* sleeping tasks and completes any pending operations that can be fulfilled.
* Semaphores are actively given to waiting tasks (necessary for FIFO).
@@ -989,6 +988,31 @@ static void do_smart_update(struct sem_a
set_semotime(sma, sops);
}
+/*
+ * check_qop: Test how often a queued operation sleeps on the semaphore semnum
+ */
+static int check_qop(struct sem_array *sma, int semnum, struct sem_queue *q,
+ bool count_zero)
+{
+ struct sembuf *sops = q->sops;
+ int nsops = q->nsops;
+ int i, semcnt;
+
+ semcnt = 0;
+
+ for (i = 0; i < nsops; i++) {
+ if (sops[i].sem_num != semnum)
+ continue;
+ if (sops[i].sem_flg & IPC_NOWAIT)
+ continue;
+ if (count_zero && sops[i].sem_op == 0)
+ semcnt++;
+ if (!count_zero && sops[i].sem_op < 0)
+ semcnt++;
+ }
+ return semcnt;
+}
+
/* The following counts are associated to each semaphore:
* semncnt number of tasks waiting on semval being nonzero
* semzcnt number of tasks waiting on semval being zero
@@ -998,66 +1022,37 @@ static void do_smart_update(struct sem_a
* The counts we return here are a rough approximation, but still
* warrant that semncnt+semzcnt>0 if the task is on the pending queue.
*/
-static int count_semncnt(struct sem_array *sma, ushort semnum)
+static int count_semcnt(struct sem_array *sma, ushort semnum,
+ bool count_zero)
{
- int semncnt;
+ struct list_head *l;
struct sem_queue *q;
+ int semcnt;
- semncnt = 0;
- list_for_each_entry(q, &sma->sem_base[semnum].pending_alter, list) {
- struct sembuf *sops = q->sops;
- BUG_ON(sops->sem_num != semnum);
- if ((sops->sem_op < 0) && !(sops->sem_flg & IPC_NOWAIT))
- semncnt++;
- }
-
- list_for_each_entry(q, &sma->pending_alter, list) {
- struct sembuf *sops = q->sops;
- int nsops = q->nsops;
- int i;
- for (i = 0; i < nsops; i++)
- if (sops[i].sem_num == semnum
- && (sops[i].sem_op < 0)
- && !(sops[i].sem_flg & IPC_NOWAIT))
- semncnt++;
- }
- return semncnt;
-}
-
-static int count_semzcnt(struct sem_array *sma, ushort semnum)
-{
- int semzcnt;
- struct sem_queue *q;
+ semcnt = 0;
+ /* First: check the simple operations. They are easy to evaluate */
+ if (count_zero)
+ l = &sma->sem_base[semnum].pending_const;
+ else
+ l = &sma->sem_base[semnum].pending_alter;
- semzcnt = 0;
- list_for_each_entry(q, &sma->sem_base[semnum].pending_const, list) {
- struct sembuf *sops = q->sops;
- BUG_ON(sops->sem_num != semnum);
- if ((sops->sem_op == 0) && !(sops->sem_flg & IPC_NOWAIT))
- semzcnt++;
+ list_for_each_entry(q, l, list) {
+ /* all task on a per-semaphore list sleep on exactly
+ * that semaphore
+ */
+ semcnt++;
}
- list_for_each_entry(q, &sma->pending_const, list) {
- struct sembuf *sops = q->sops;
- int nsops = q->nsops;
- int i;
- for (i = 0; i < nsops; i++)
- if (sops[i].sem_num == semnum
- && (sops[i].sem_op == 0)
- && !(sops[i].sem_flg & IPC_NOWAIT))
- semzcnt++;
- }
+ /* Then: check the complex operations. */
list_for_each_entry(q, &sma->pending_alter, list) {
- struct sembuf *sops = q->sops;
- int nsops = q->nsops;
- int i;
- for (i = 0; i < nsops; i++)
- if (sops[i].sem_num == semnum
- && (sops[i].sem_op == 0)
- && !(sops[i].sem_flg & IPC_NOWAIT))
- semzcnt++;
+ semcnt += check_qop(sma, semnum, q, count_zero);
+ }
+ if (count_zero) {
+ list_for_each_entry(q, &sma->pending_const, list) {
+ semcnt += check_qop(sma, semnum, q, count_zero);
+ }
}
- return semzcnt;
+ return semcnt;
}
/* Free a semaphore set. freeary() is called with sem_ids.rwsem locked
@@ -1459,10 +1454,10 @@ static int semctl_main(struct ipc_namesp
err = curr->sempid;
goto out_unlock;
case GETNCNT:
- err = count_semncnt(sma, semnum);
+ err = count_semcnt(sma, semnum, 0);
goto out_unlock;
case GETZCNT:
- err = count_semzcnt(sma, semnum);
+ err = count_semcnt(sma, semnum, 1);
goto out_unlock;
}
_
Patches currently in -mm which might be from manfred@xxxxxxxxxxxxxxxx are
ipc-constify-ipc_ops.patch
ipc-shmc-check-for-ulong-overflows-in-shmat.patch
ipc-shmc-check-for-overflows-of-shm_tot.patch
ipc-shmc-check-for-integer-overflow-during-shmget.patch
ipc-shmc-increase-the-defaults-for-shmall-shmmax.patch
ipcshm-document-new-limits-in-the-uapi-header.patch
ipcshm-document-new-limits-in-the-uapi-header-v2.patch
ipcshm-document-new-limits-in-the-uapi-header-v3.patch
ipcmsg-use-current-state-helpers.patch
ipcmsg-move-some-msgq-ns-code-around.patch
ipcmsg-document-volatile-r_msg.patch
ipc-semc-bugfix-for-semctlgetzcnt.patch
ipc-semc-remove-code-duplication.patch
ipc-semc-change-perform_atomic_semop-parameters.patch
ipc-semc-store-which-operation-blocks-in-perform_atomic_semop.patch
ipc-semc-make-semctlgetncntgetzcnt-standard-compliant.patch
slab-leaks3-default-y.patch
--
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
