Subject: + ipcmsg-always-respect-msg_noerror.patch added to -mm tree
To: davidlohr@xxxxxx,aswin@xxxxxx,manfred@xxxxxxxxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Tue, 13 May 2014 13:39:28 -0700
The patch titled
Subject: ipc,msg: always respect MSG_NOERROR
has been added to the -mm tree. Its filename is
ipcmsg-always-respect-msg_noerror.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/ipcmsg-always-respect-msg_noerror.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/ipcmsg-always-respect-msg_noerror.patch
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From: Davidlohr Bueso <davidlohr@xxxxxx>
Subject: ipc,msg: always respect MSG_NOERROR
When specifying the MSG_NOERROR flag, receivers can avoid returning error
(E2BIG) and just truncate the message text, if it is too large.
Currently, this logic is only respected when there are already pending
messages in the queue. Fix this for the case when there are only
receivers waiting for a msg to be sent. In order for this to work, save
the flags in the msg_receiver struct as it must be used later when doing
the pipeline send.
Also do some pipeline_send() cleanups while at it.
Signed-off-by: Davidlohr Bueso <davidlohr@xxxxxx>
Cc: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
Cc: Aswin Chandramouleeswaran <aswin@xxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
ipc/msg.c | 63 ++++++++++++++++++++++++++++------------------------
1 file changed, 35 insertions(+), 28 deletions(-)
diff -puN ipc/msg.c~ipcmsg-always-respect-msg_noerror ipc/msg.c
--- a/ipc/msg.c~ipcmsg-always-respect-msg_noerror
+++ a/ipc/msg.c
@@ -50,6 +50,7 @@ struct msg_receiver {
struct task_struct *r_tsk;
int r_mode;
+ int r_msgflg;
long r_msgtype;
long r_maxsize;
@@ -562,42 +563,47 @@ static int testmsg(struct msg_msg *msg,
return 0;
}
-static inline int pipelined_send(struct msg_queue *msq, struct msg_msg *msg)
+static inline bool pipelined_send(struct msg_queue *msq, struct msg_msg *msg)
{
struct msg_receiver *msr, *t;
list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) {
- if (testmsg(msg, msr->r_msgtype, msr->r_mode) &&
- !security_msg_queue_msgrcv(msq, msg, msr->r_tsk,
- msr->r_msgtype, msr->r_mode)) {
-
- list_del(&msr->r_list);
- if (msr->r_maxsize < msg->m_ts) {
- /* initialize pipelined send ordering */
- msr->r_msg = NULL;
- wake_up_process(msr->r_tsk);
- smp_mb(); /* see barrier comment below */
- msr->r_msg = ERR_PTR(-E2BIG);
- } else {
- msr->r_msg = NULL;
- msq->q_lrpid = task_pid_vnr(msr->r_tsk);
- msq->q_rtime = get_seconds();
- wake_up_process(msr->r_tsk);
- /*
- * Ensure that the wakeup is visible before
- * setting r_msg, as the receiving end depends
- * on it. See lockless receive part 1 and 2 in
- * do_msgrcv().
- */
- smp_mb();
- msr->r_msg = msg;
+ if (!testmsg(msg, msr->r_msgtype, msr->r_mode))
+ continue;
+ if (security_msg_queue_msgrcv(msq, msg, msr->r_tsk,
+ msr->r_msgtype, msr->r_mode))
+ continue;
+
+ /* found a suitable receiver, time to dequeue and wake */
+ list_del(&msr->r_list);
+
+ /* initialize pipelined send ordering */
+ msr->r_msg = NULL;
+
+ if (msr->r_maxsize < msg->m_ts &&
+ !(msr->r_msgflg & MSG_NOERROR)) {
+ wake_up_process(msr->r_tsk);
+ smp_mb(); /* see barrier comment below */
+ msr->r_msg = ERR_PTR(-E2BIG);
+ } else {
+ msq->q_lrpid = task_pid_vnr(msr->r_tsk);
+ msq->q_rtime = get_seconds();
+ wake_up_process(msr->r_tsk);
- return 1;
- }
+ /*
+ * Ensure that the wakeup is visible before
+ * setting r_msg, as the receiving end depends
+ * on it. See lockless receive part 1 and 2 in
+ * do_msgrcv().
+ */
+ smp_mb();
+ msr->r_msg = msg;
+
+ return true;
}
}
- return 0;
+ return false; /* no receivers on the other side */
}
long do_msgsnd(int msqid, long mtype, void __user *mtext,
@@ -901,6 +907,7 @@ long do_msgrcv(int msqid, void __user *b
list_add_tail(&msr_d.r_list, &msq->q_receivers);
msr_d.r_tsk = current;
msr_d.r_msgtype = msgtyp;
+ msr_d.r_msgflg = msgflg;
msr_d.r_mode = mode;
if (msgflg & MSG_NOERROR)
msr_d.r_maxsize = INT_MAX;
_
Patches currently in -mm which might be from davidlohr@xxxxxx are
mmvmacache-add-debug-data.patch
mmvmacache-optimize-overflow-system-wide-flushing.patch
mm-pass-vm_bug_on-reason-to-dump_page.patch
mm-pass-vm_bug_on-reason-to-dump_page-fix.patch
hugetlb-prep_compound_gigantic_page-drop-__init-marker.patch
hugetlb-add-hstate_is_gigantic.patch
hugetlb-update_and_free_page-dont-clear-pg_reserved-bit.patch
hugetlb-move-helpers-up-in-the-file.patch
hugetlb-add-support-for-gigantic-page-allocation-at-runtime.patch
m68k-call-find_vma-with-the-mmap_sem-held-in-sys_cacheflush.patch
mips-call-find_vma-with-the-mmap_sem-held.patch
arc-call-find_vma-with-the-mmap_sem-held.patch
arc-call-find_vma-with-the-mmap_sem-held-fix.patch
drm-exynos-call-find_vma-with-the-mmap_sem-held.patch
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
ipcmsg-use-current-state-helpers.patch
ipcmsg-move-some-msgq-ns-code-around.patch
ipcmsg-always-respect-msg_noerror.patch
ipcmsg-document-volatile-r_msg.patch
ipcmsg-loosen-check-for-full-queue.patch
linux-next.patch
blackfin-ptrace-call-find_vma-with-the-mmap_sem-held.patch
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