Module Name: src
Committed By: pooka
Date: Wed Jan 14 18:46:38 UTC 2015
Modified Files:
src/sys/rump/librump/rumpkern: intr.c
Log Message:
Implement softint_schedule_cpu() for rump kernels.
While distributing processing all over the place is not relevant for
high-performance rump kernel I/O stacks (and downright counterproductive),
the mechanism is used e.g. to reach a quiescent state when detaching
an interface, and therefore a semantically correct implementation is
required.
Fixes at least an uncommon race in the ifconfig destroy case.
reported & patch tested by Justin Cormack.
To generate a diff of this commit:
cvs rdiff -u -r1.46 -r1.47 src/sys/rump/librump/rumpkern/intr.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/rump/librump/rumpkern/intr.c
diff -u src/sys/rump/librump/rumpkern/intr.c:1.46 src/sys/rump/librump/rumpkern/intr.c:1.47
--- src/sys/rump/librump/rumpkern/intr.c:1.46 Sun Jun 22 20:09:19 2014
+++ src/sys/rump/librump/rumpkern/intr.c Wed Jan 14 18:46:38 2015
@@ -1,4 +1,4 @@
-/* $NetBSD: intr.c,v 1.46 2014/06/22 20:09:19 pooka Exp $ */
+/* $NetBSD: intr.c,v 1.47 2015/01/14 18:46:38 pooka Exp $ */
/*
* Copyright (c) 2008-2010 Antti Kantee. All Rights Reserved.
@@ -26,7 +26,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: intr.c,v 1.46 2014/06/22 20:09:19 pooka Exp $");
+__KERNEL_RCSID(0, "$NetBSD: intr.c,v 1.47 2015/01/14 18:46:38 pooka Exp $");
#include <sys/param.h>
#include <sys/atomic.h>
@@ -62,8 +62,10 @@ struct softint {
struct softint_percpu {
struct softint *sip_parent;
bool sip_onlist;
+ bool sip_onlist_cpu;
- LIST_ENTRY(softint_percpu) sip_entries;
+ LIST_ENTRY(softint_percpu) sip_entries; /* scheduled */
+ TAILQ_ENTRY(softint_percpu) sip_entries_cpu; /* to be scheduled */
};
struct softint_lev {
@@ -71,6 +73,11 @@ struct softint_lev {
LIST_HEAD(, softint_percpu) si_pending;
};
+static TAILQ_HEAD(, softint_percpu) sicpupending \
+ = TAILQ_HEAD_INITIALIZER(sicpupending);
+static struct rumpuser_mtx *sicpumtx;
+static struct rumpuser_cv *sicpucv;
+
kcondvar_t lbolt; /* Oh Kath Ra */
static u_int ticks;
@@ -183,6 +190,51 @@ sithread(void *arg)
panic("sithread unreachable");
}
+/*
+ * Helper for softint_schedule_cpu()
+ */
+static void
+sithread_cpu_bouncer(void *arg)
+{
+ struct lwp *me;
+
+ me = curlwp;
+ me->l_pflag |= LP_BOUND;
+
+ rump_unschedule();
+ for (;;) {
+ struct softint_percpu *sip;
+ struct softint *si;
+ struct cpu_info *ci;
+ unsigned int cidx;
+
+ rumpuser_mutex_enter_nowrap(sicpumtx);
+ while (TAILQ_EMPTY(&sicpupending)) {
+ rumpuser_cv_wait_nowrap(sicpucv, sicpumtx);
+ }
+ sip = TAILQ_FIRST(&sicpupending);
+ TAILQ_REMOVE(&sicpupending, sip, sip_entries_cpu);
+ sip->sip_onlist_cpu = false;
+ rumpuser_mutex_exit(sicpumtx);
+
+ /*
+ * ok, now figure out which cpu we need the softint to
+ * be handled on
+ */
+ si = sip->sip_parent;
+ cidx = sip - si->si_entry;
+ ci = cpu_lookup(cidx);
+ me->l_target_cpu = ci;
+
+ /* schedule ourselves there, and then schedule the softint */
+ rump_schedule();
+ KASSERT(curcpu() == ci);
+ softint_schedule(si);
+ rump_unschedule();
+ }
+ panic("sithread_cpu_bouncer unreasonable");
+}
+
static kmutex_t sithr_emtx;
static unsigned int sithr_est;
static int sithr_canest;
@@ -273,6 +325,13 @@ softint_init(struct cpu_info *ci)
if ((rv = kthread_create(PRI_NONE, KTHREAD_MPSAFE,
ci, doclock, NULL, NULL, "rumpclk%d", ci->ci_index)) != 0)
panic("clock thread creation failed: %d", rv);
+
+ /* not one either, but at least a softint helper */
+ rumpuser_mutex_init(&sicpumtx, RUMPUSER_MTX_SPIN);
+ rumpuser_cv_init(&sicpucv);
+ if ((rv = kthread_create(PRI_NONE, KTHREAD_MPSAFE,
+ NULL, sithread_cpu_bouncer, NULL, NULL, "sipbnc")) != 0)
+ panic("softint cpu bouncer creation failed: %d", rv);
}
void *
@@ -300,6 +359,13 @@ softint_establish(u_int flags, void (*fu
return si;
}
+static struct softint_percpu *
+sitosip(struct softint *si, struct cpu_info *ci)
+{
+
+ return &si->si_entry[ci->ci_index];
+}
+
/*
* Soft interrupts bring two choices. If we are running with thread
* support enabled, defer execution, otherwise execute in place.
@@ -310,7 +376,7 @@ softint_schedule(void *arg)
{
struct softint *si = arg;
struct cpu_info *ci = curcpu();
- struct softint_percpu *sip = &si->si_entry[ci->ci_index];
+ struct softint_percpu *sip = sitosip(si, ci);
struct cpu_data *cd = &ci->ci_data;
struct softint_lev *si_lvl = cd->cpu_softcpu;
@@ -325,14 +391,44 @@ softint_schedule(void *arg)
}
}
+/*
+ * Like softint_schedule(), except schedule softint to be handled on
+ * the core designated by ci_tgt instead of the core the call is made on.
+ *
+ * Unlike softint_schedule(), the performance is not important
+ * (unless ci_tgt == curcpu): high-performance rump kernel I/O stacks
+ * should arrange data to already be on the right core at the driver
+ * layer.
+ */
void
-softint_schedule_cpu(void *arg, struct cpu_info *ci)
+softint_schedule_cpu(void *arg, struct cpu_info *ci_tgt)
{
+ struct softint *si = arg;
+ struct cpu_info *ci_cur = curcpu();
+ struct softint_percpu *sip;
+
+ KASSERT(rump_threads);
+
+ /* preferred case (which can be optimized some day) */
+ if (ci_cur == ci_tgt) {
+ softint_schedule(si);
+ return;
+ }
+
/*
- * TODO: implement this properly
+ * no? then it's softint turtles all the way down
*/
- KASSERT(curcpu() == ci);
- softint_schedule(arg);
+
+ sip = sitosip(si, ci_tgt);
+ rumpuser_mutex_enter_nowrap(sicpumtx);
+ if (sip->sip_onlist_cpu) {
+ rumpuser_mutex_exit(sicpumtx);
+ return;
+ }
+ TAILQ_INSERT_TAIL(&sicpupending, sip, sip_entries_cpu);
+ sip->sip_onlist_cpu = true;
+ rumpuser_cv_signal(sicpucv);
+ rumpuser_mutex_exit(sicpumtx);
}
/*
