linux-kernel - [PATCH v4 26/36] hrtimer: Add clock bases and hrtimer mode for soft irq context

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Date:   Thu, 21 Dec 2017 11:41:55 +0100
From:   Anna-Maria Gleixner <anna-maria@...utronix.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>, keescook@...omium.org,
        Christoph Hellwig <hch@....de>,
        John Stultz <john.stultz@...aro.org>,
        Anna-Maria Gleixner <anna-maria@...utronix.de>
Subject: [PATCH v4 26/36] hrtimer: Add clock bases and hrtimer mode for soft irq context

hrtimer callback functions are always executed in hard interrupt
context. Users of hrtimer which need their timer function to be executed
in soft interrupt context, make use of tasklets to get the proper context.

Add additional hrtimer clock bases for timers which must expire in softirq
context, so the detour via the tasklet can be avoided. This is also
required for RT, where the majority of hrtimer is moved into softirq
hrtimer context.

The selection of the expiry mode happens via a mode bit. Introduce
HRTIMER_MODE_SOFT and the matching combinations with the ABS/REL/PINNED
bits and update the decoding of hrtimer_mode in tracepoints.

Signed-off-by: Anna-Maria Gleixner <anna-maria@...utronix.de>
---
 include/linux/hrtimer.h      | 14 ++++++++++++++
 include/trace/events/timer.h |  6 +++++-
 kernel/time/hrtimer.c        | 20 ++++++++++++++++++++
 3 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h
index 98ed35767ac5..26ae8a868ea8 100644
--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -33,14 +33,24 @@ struct hrtimer_cpu_base;
  * HRTIMER_MODE_REL		- Time value is relative to now
  * HRTIMER_MODE_PINNED		- Timer is bound to CPU (is only considered
  *				  when starting the timer)
+ * HRTIMER_MODE_SOFT		- Timer callback function will be executed in
+ *				  soft irq context
  */
 enum hrtimer_mode {
 	HRTIMER_MODE_ABS	= 0x00,
 	HRTIMER_MODE_REL	= 0x01,
 	HRTIMER_MODE_PINNED	= 0x02,
+	HRTIMER_MODE_SOFT	= 0x04,
 
 	HRTIMER_MODE_ABS_PINNED = HRTIMER_MODE_ABS | HRTIMER_MODE_PINNED,
 	HRTIMER_MODE_REL_PINNED = HRTIMER_MODE_REL | HRTIMER_MODE_PINNED,
+
+	HRTIMER_MODE_ABS_SOFT	= HRTIMER_MODE_ABS | HRTIMER_MODE_SOFT,
+	HRTIMER_MODE_REL_SOFT	= HRTIMER_MODE_REL | HRTIMER_MODE_SOFT,
+
+	HRTIMER_MODE_ABS_PINNED_SOFT = HRTIMER_MODE_ABS_PINNED | HRTIMER_MODE_SOFT,
+	HRTIMER_MODE_REL_PINNED_SOFT = HRTIMER_MODE_REL_PINNED | HRTIMER_MODE_SOFT,
+
 };
 
 /*
@@ -151,6 +161,10 @@ enum  hrtimer_base_type {
 	HRTIMER_BASE_REALTIME,
 	HRTIMER_BASE_BOOTTIME,
 	HRTIMER_BASE_TAI,
+	HRTIMER_BASE_MONOTONIC_SOFT,
+	HRTIMER_BASE_REALTIME_SOFT,
+	HRTIMER_BASE_BOOTTIME_SOFT,
+	HRTIMER_BASE_TAI_SOFT,
 	HRTIMER_MAX_CLOCK_BASES,
 };
 
diff --git a/include/trace/events/timer.h b/include/trace/events/timer.h
index 744b4310b24b..a57e4ee989d6 100644
--- a/include/trace/events/timer.h
+++ b/include/trace/events/timer.h
@@ -148,7 +148,11 @@ DEFINE_EVENT(timer_class, timer_cancel,
 		{ HRTIMER_MODE_ABS,		"ABS"		},	\
 		{ HRTIMER_MODE_REL,		"REL"		},	\
 		{ HRTIMER_MODE_ABS_PINNED,	"ABS|PINNED"	},	\
-		{ HRTIMER_MODE_REL_PINNED,	"REL|PINNED"	})
+		{ HRTIMER_MODE_REL_PINNED,	"REL|PINNED"	},	\
+		{ HRTIMER_MODE_ABS_SOFT,	"ABS|SOFT"	},	\
+		{ HRTIMER_MODE_REL_SOFT,	"REL|SOFT"	},	\
+		{ HRTIMER_MODE_ABS_PINNED_SOFT,	"ABS|PINNED|SOFT" },	\
+		{ HRTIMER_MODE_REL_PINNED_SOFT,	"REL|PINNED|SOFT" })
 
 /**
  * hrtimer_init - called when the hrtimer is initialized
diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index 1966867f7232..74598e3da748 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -92,6 +92,26 @@ DEFINE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases) =
 			.clockid = CLOCK_TAI,
 			.get_time = &ktime_get_clocktai,
 		},
+		{
+			.index = HRTIMER_BASE_MONOTONIC_SOFT,
+			.clockid = CLOCK_MONOTONIC,
+			.get_time = &ktime_get,
+		},
+		{
+			.index = HRTIMER_BASE_REALTIME_SOFT,
+			.clockid = CLOCK_REALTIME,
+			.get_time = &ktime_get_real,
+		},
+		{
+			.index = HRTIMER_BASE_BOOTTIME_SOFT,
+			.clockid = CLOCK_BOOTTIME,
+			.get_time = &ktime_get_boottime,
+		},
+		{
+			.index = HRTIMER_BASE_TAI_SOFT,
+			.clockid = CLOCK_TAI,
+			.get_time = &ktime_get_clocktai,
+		},
 	}
 };
 
-- 
2.11.0