From: Hongzhan Chen <hongzhan.chen@intel.com>
To: xenomai@xenomai.org
Subject: [[next]PATCH v2] cobalt/thread: move inband work descriptions off the stack
Date: Wed, 9 Jun 2021 22:14:38 -0400 [thread overview]
Message-ID: <20210610021438.8004-1-hongzhan.chen@intel.com> (raw)
Unlike the I-pipe, Dovetail does not copy the work descriptor but
merely hands over the request to the common irq_work() mechanism. We
must guarantee that such descriptor lives in a portion of memory which
won't go stale until the handler has run, which by design can only
happen once the calling out-of-band context unwinds.
Therefore, we have to add one or more "signal slots" per possible
cause of in-band signal into this thread's control block.
For SIGDEBUG, except SIGDEBUG_WATCHDOG all other SIGDEBUG_* cause
including SIGDEBUG_MIGRATE_SIGNAL, SIGDEBUG_MIGRATE_SYSCALL,
SIGDEBUG_MIGRATE_FAULT, SIGDEBUG_MIGRATE_PRIOINV, SIGDEBUG_NOMLOCK,
SIGDEBUG_RESCNT_IMBALANCE, SIGDEBUG_LOCK_BREAK, SIGDEBUG_MUTEX_SLEEP
are synchronous and mutually exclusive due to the oob->in-band transition.
But SIGDEBUG_WATCHDOG is triggered asynchronously by the oob timer.
All SIGSHADOW_* events need their own slot: SIGSHADOW_ACTION_HARDEN and
SIGSHADOW_ACTION_HOME can be raised by remote threads asynchronously to
the target thread. SIGSHADOW_ACTION_BACKTRACE comes in addition to
SIGDEBUG_MIGRATE_*. For the latter reason, SIGSHADOW_ACTION_BACKTRACE
cannot pile up though.
Including SIGTERM, we have totally 6 slots.
Signed-off-by: Hongzhan Chen <hongzhan.chen@intel.com>
diff --git a/include/cobalt/kernel/thread.h b/include/cobalt/kernel/thread.h
index c92037bfe..0c5eacda7 100644
--- a/include/cobalt/kernel/thread.h
+++ b/include/cobalt/kernel/thread.h
@@ -23,6 +23,7 @@
#include <linux/sched.h>
#include <linux/sched/rt.h>
#include <pipeline/thread.h>
+#include <pipeline/inband_work.h>
#include <cobalt/kernel/list.h>
#include <cobalt/kernel/stat.h>
#include <cobalt/kernel/timer.h>
@@ -42,6 +43,14 @@
#define XNTHREAD_BLOCK_BITS (XNSUSP|XNPEND|XNDELAY|XNDORMANT|XNRELAX|XNHELD|XNDBGSTOP)
#define XNTHREAD_MODE_BITS (XNRRB|XNWARN|XNTRAPLB)
+#define XNTHREAD_SIGNALS_NUM 6
+#define XNTHREAD_SIGDEBUG_NONWATCHDOG 0
+#define XNTHREAD_SIGDEBUG_WATCHDOD 1
+#define XNTHREAD_SIGSHADOW_HARDEN 2
+#define XNTHREAD_SIGSHADOW_BACKTRACE 3
+#define XNTHREAD_SIGSHADOW_HOME 4
+#define XNTHREAD_SIGTERM 5
+
struct xnthread;
struct xnsched;
struct xnselector;
@@ -50,6 +59,13 @@ struct xnsched_tpslot;
struct xnthread_personality;
struct completion;
+struct lostage_signal {
+ struct pipeline_inband_work inband_work; /* Must be first. */
+ struct task_struct *task;
+ int signo, sigval;
+ struct lostage_signal *self; /* Revisit: I-pipe requirement */
+};
+
struct xnthread_init_attr {
struct xnthread_personality *personality;
cpumask_t affinity;
@@ -199,6 +215,29 @@ struct xnthread {
const char *exe_path; /* Executable path */
u32 proghash; /* Hash value for exe_path */
#endif
+ /*
+ * Each slot handle different cause of signal
+ * slot 0:
+ * SIGDEBUG_MIGRATE_SIGNAL
+ * SIGDEBUG_MIGRATE_SYSCALL
+ * SIGDEBUG_MIGRATE_FAULT
+ * SIGDEBUG_MIGRATE_PRIOINV
+ * SIGDEBUG_NOMLOCK
+ * SIGDEBUG_RESCNT_IMBALANCE
+ * SIGDEBUG_LOCK_BREAK
+ * SIGDEBUG_MUTEX_SLEEP
+ * slot 1:
+ * SIGDEBUG_WATCHDOG
+ * slot 2:
+ * SIGSHADOW_ACTION_HARDEN
+ * slot 3:
+ * SIGSHADOW_ACTION_BACKTRACE
+ * slot 4:
+ * SIGSHADOW_ACTION_HOME
+ * slot 5:
+ * SIGTERM
+ */
+ struct lostage_signal sigarray[XNTHREAD_SIGNALS_NUM];
};
static inline int xnthread_get_state(const struct xnthread *thread)
diff --git a/kernel/cobalt/thread.c b/kernel/cobalt/thread.c
index d3a827eaa..d180aa85c 100644
--- a/kernel/cobalt/thread.c
+++ b/kernel/cobalt/thread.c
@@ -2083,12 +2083,6 @@ void xnthread_relax(int notify, int reason)
}
EXPORT_SYMBOL_GPL(xnthread_relax);
-struct lostage_signal {
- struct pipeline_inband_work inband_work; /* Must be first. */
- struct task_struct *task;
- int signo, sigval;
-};
-
static inline void do_kthread_signal(struct task_struct *p,
struct xnthread *thread,
struct lostage_signal *rq)
@@ -2112,7 +2106,7 @@ static void lostage_task_signal(struct pipeline_inband_work *inband_work)
thread = xnthread_from_task(p);
if (thread && !xnthread_test_state(thread, XNUSER)) {
do_kthread_signal(p, thread, rq);
- return;
+ goto out;
}
signo = rq->signo;
@@ -2127,6 +2121,8 @@ static void lostage_task_signal(struct pipeline_inband_work *inband_work)
send_sig_info(signo, &si, p);
} else
send_sig(signo, p, 1);
+out:
+ memset(rq->self, 0, sizeof(*rq));
}
static int force_wakeup(struct xnthread *thread) /* nklock locked, irqs off */
@@ -2288,19 +2284,77 @@ void xnthread_demote(struct xnthread *thread)
}
EXPORT_SYMBOL_GPL(xnthread_demote);
+static int get_slot_index_from_sig(int sig, int arg)
+{
+ int action;
+
+ switch (sig) {
+ case SIGDEBUG:
+ switch (arg) {
+ case SIGDEBUG_WATCHDOG:
+ return XNTHREAD_SIGDEBUG_WATCHDOD;
+ case SIGDEBUG_MIGRATE_SIGNAL:
+ case SIGDEBUG_MIGRATE_SYSCALL:
+ case SIGDEBUG_MIGRATE_FAULT:
+ case SIGDEBUG_MIGRATE_PRIOINV:
+ case SIGDEBUG_NOMLOCK:
+ case SIGDEBUG_RESCNT_IMBALANCE:
+ case SIGDEBUG_LOCK_BREAK:
+ case SIGDEBUG_MUTEX_SLEEP:
+ return XNTHREAD_SIGDEBUG_NONWATCHDOG;
+ }
+ break;
+ case SIGSHADOW:
+ action = sigshadow_action(arg);
+ switch (action) {
+ case SIGSHADOW_ACTION_HARDEN:
+ return XNTHREAD_SIGSHADOW_HARDEN;
+ case SIGSHADOW_ACTION_BACKTRACE:
+ return XNTHREAD_SIGSHADOW_BACKTRACE;
+ case SIGSHADOW_ACTION_HOME:
+ return XNTHREAD_SIGSHADOW_HOME;
+ }
+ break;
+ case SIGTERM:
+ return XNTHREAD_SIGTERM;
+ }
+
+ return -1;
+}
+
void xnthread_signal(struct xnthread *thread, int sig, int arg)
{
- struct lostage_signal sigwork = {
- .inband_work = PIPELINE_INBAND_WORK_INITIALIZER(sigwork,
- lostage_task_signal),
- .task = xnthread_host_task(thread),
- .signo = sig,
- .sigval = sig == SIGDEBUG ? arg | sigdebug_marker : arg,
- };
+ struct lostage_signal *sigwork;
+ int slot;
+
+ slot = get_slot_index_from_sig(sig, arg);
+
+ if (WARN_ON(slot < 0))
+ return;
+
+ sigwork = &thread->sigarray[slot];
+
+ /* To avoid invalidating the already submitted event
+ * if previous submitted has not been handled as we expected
+ * because setting sigwork->self zero is final step
+ * in handling sig.
+ */
+ if (WARN_ON((sigwork->self != NULL) &&
+ (sigwork->self == sigwork))) {
+ return;
+ }
+
+ sigwork->inband_work = (struct pipeline_inband_work)
+ PIPELINE_INBAND_WORK_INITIALIZER(*sigwork,
+ lostage_task_signal);
+ sigwork->task = xnthread_host_task(thread);
+ sigwork->signo = sig;
+ sigwork->sigval = sig == SIGDEBUG ? arg | sigdebug_marker : arg;
+ sigwork->self = sigwork; /* Revisit: I-pipe requirement */
- trace_cobalt_lostage_request("signal", sigwork.task);
+ trace_cobalt_lostage_request("signal", sigwork->task);
- pipeline_post_inband_work(&sigwork);
+ pipeline_post_inband_work(sigwork);
}
EXPORT_SYMBOL_GPL(xnthread_signal);
--
2.17.1
next reply other threads:[~2021-06-10 2:14 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-10 2:14 Hongzhan Chen [this message]
2021-06-10 15:42 ` [[next]PATCH v2] cobalt/thread: move inband work descriptions off the stack Jan Kiszka
2021-06-11 8:27 ` Jan Kiszka
2021-06-15 2:21 ` Chen, Hongzhan
2021-06-15 6:42 ` Jan Kiszka
2021-06-16 2:45 ` Chen, Hongzhan
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