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 <[email protected]> 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
