Module: xenomai-jki
Branch: for-upstream
Commit: f558b46e2efb97335c3251f079c6405ea0b36c80
URL:    
http://git.xenomai.org/?p=xenomai-jki.git;a=commit;h=f558b46e2efb97335c3251f079c6405ea0b36c80

Author: Jan Kiszka <jan.kis...@siemens.com>
Date:   Tue Nov 10 23:07:48 2009 +0100

nucleus: Cosmetic cleanup of lostage_handler

Granted, it's unlikely that we will ever hit the last free slot and will
then actually be preempted by the real-time domain that injects another
request. If we were, the slot may be overwritten too early. Let's clean
this up, at least for the sake of the reader that tries to grab the
logic.

Signed-off-by: Jan Kiszka <jan.kis...@siemens.com>

---

 ksrc/nucleus/shadow.c |   24 +++++++++++++++---------
 1 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/ksrc/nucleus/shadow.c b/ksrc/nucleus/shadow.c
index 1eae0a1..e924637 100644
--- a/ksrc/nucleus/shadow.c
+++ b/ksrc/nucleus/shadow.c
@@ -716,20 +716,27 @@ static void xnshadow_dereference_skin(unsigned magic)
 
 static void lostage_handler(void *cookie)
 {
-       int cpu = smp_processor_id(), reqnum, sig, arg;
-       struct __lostagerq *rq = &lostagerq[cpu];
+       struct __lostagerq *rq = &lostagerq[smp_processor_id()];
+       int reqnum, type, arg, sig, sigarg;
+       struct task_struct *p;
 
        while ((reqnum = rq->out) != rq->in) {
-               struct task_struct *p = rq->req[reqnum].task;
+               type = rq->req[reqnum].type;
+               p = rq->req[reqnum].task;
+               arg = rq->req[reqnum].arg;
+
+               /* make sure we read the request before releasing its slot */
+               barrier();
+
                rq->out = (reqnum + 1) & (LO_MAX_REQUESTS - 1);
 
                trace_mark(xn_nucleus, lostage_work,
                           "reqnum %d comm %s pid %d",
                           reqnum, p->comm, p->pid);
 
-               switch (rq->req[reqnum].type) {
+               switch (type) {
                case LO_UNMAP_REQ:
-                       xnshadow_dereference_skin(rq->req[reqnum].arg);
+                       xnshadow_dereference_skin(arg);
 
                        /* fall through */
                case LO_WAKEUP_REQ:
@@ -751,21 +758,20 @@ static void lostage_handler(void *cookie)
                        break;
 
                case LO_SIGTHR_REQ:
-                       xnshadow_sig_demux(rq->req[reqnum].arg, sig, arg);
+                       xnshadow_sig_demux(arg, sig, sigarg);
                        if (sig == SIGSHADOW) {
                                siginfo_t si;
                                memset(&si, '\0', sizeof(si));
                                si.si_signo = sig;
                                si.si_code = SI_QUEUE;
-                               si.si_int = arg;
+                               si.si_int = sigarg;
                                send_sig_info(sig, &si, p);
                        } else
                                send_sig(sig, p, 1);
                        break;
 
                case LO_SIGGRP_REQ:
-                       sig = rq->req[reqnum].arg;
-                       kill_proc(p->pid, sig, 1);
+                       kill_proc(p->pid, arg, 1);
                        break;
                }
        }


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