diff options
Diffstat (limited to 'debian/patches-rt/0006-printk-rb-add-blocking-reader-support.patch')
| -rw-r--r-- | debian/patches-rt/0006-printk-rb-add-blocking-reader-support.patch | 162 |
1 files changed, 0 insertions, 162 deletions
diff --git a/debian/patches-rt/0006-printk-rb-add-blocking-reader-support.patch b/debian/patches-rt/0006-printk-rb-add-blocking-reader-support.patch deleted file mode 100644 index f3ab52e2a..000000000 --- a/debian/patches-rt/0006-printk-rb-add-blocking-reader-support.patch +++ /dev/null @@ -1,162 +0,0 @@ -From: John Ogness <john.ogness@linutronix.de> -Date: Tue, 12 Feb 2019 15:29:44 +0100 -Subject: [PATCH 06/25] printk-rb: add blocking reader support -Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.9/older/patches-5.9-rt16.tar.xz - -Add a blocking read function for readers. An irq_work function is -used to signal the wait queue so that write notification can -be triggered from any context. - -Signed-off-by: John Ogness <john.ogness@linutronix.de> -Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> ---- - include/linux/printk_ringbuffer.h | 20 +++++++++++++ - lib/printk_ringbuffer.c | 55 ++++++++++++++++++++++++++++++++++++++ - 2 files changed, 75 insertions(+) - ---- a/include/linux/printk_ringbuffer.h -+++ b/include/linux/printk_ringbuffer.h -@@ -2,8 +2,10 @@ - #ifndef _LINUX_PRINTK_RINGBUFFER_H - #define _LINUX_PRINTK_RINGBUFFER_H - -+#include <linux/irq_work.h> - #include <linux/atomic.h> - #include <linux/percpu.h> -+#include <linux/wait.h> - - struct prb_cpulock { - atomic_t owner; -@@ -22,6 +24,10 @@ struct printk_ringbuffer { - - struct prb_cpulock *cpulock; - atomic_t ctx; -+ -+ struct wait_queue_head *wq; -+ atomic_long_t wq_counter; -+ struct irq_work *wq_work; - }; - - struct prb_entry { -@@ -59,6 +65,15 @@ struct prb_iterator { - #define DECLARE_STATIC_PRINTKRB(name, szbits, cpulockptr) \ - static char _##name##_buffer[1 << (szbits)] \ - __aligned(__alignof__(long)); \ -+static DECLARE_WAIT_QUEUE_HEAD(_##name##_wait); \ -+static void _##name##_wake_work_func(struct irq_work *irq_work) \ -+{ \ -+ wake_up_interruptible_all(&_##name##_wait); \ -+} \ -+static struct irq_work _##name##_wake_work = { \ -+ .func = _##name##_wake_work_func, \ -+ .flags = ATOMIC_INIT(IRQ_WORK_LAZY), \ -+}; \ - static struct printk_ringbuffer name = { \ - .buffer = &_##name##_buffer[0], \ - .size_bits = szbits, \ -@@ -68,6 +83,9 @@ static struct printk_ringbuffer name = { - .reserve = ATOMIC_LONG_INIT(-111 * sizeof(long)), \ - .cpulock = cpulockptr, \ - .ctx = ATOMIC_INIT(0), \ -+ .wq = &_##name##_wait, \ -+ .wq_counter = ATOMIC_LONG_INIT(0), \ -+ .wq_work = &_##name##_wake_work, \ - } - - /* writer interface */ -@@ -80,6 +98,8 @@ void prb_iter_init(struct prb_iterator * - u64 *seq); - void prb_iter_copy(struct prb_iterator *dest, struct prb_iterator *src); - int prb_iter_next(struct prb_iterator *iter, char *buf, int size, u64 *seq); -+int prb_iter_wait_next(struct prb_iterator *iter, char *buf, int size, -+ u64 *seq); - int prb_iter_data(struct prb_iterator *iter, char *buf, int size, u64 *seq); - - /* utility functions */ ---- a/lib/printk_ringbuffer.c -+++ b/lib/printk_ringbuffer.c -@@ -1,4 +1,5 @@ - // SPDX-License-Identifier: GPL-2.0 -+#include <linux/sched.h> - #include <linux/smp.h> - #include <linux/string.h> - #include <linux/errno.h> -@@ -154,6 +155,7 @@ static bool push_tail(struct printk_ring - void prb_commit(struct prb_handle *h) - { - struct printk_ringbuffer *rb = h->rb; -+ bool changed = false; - struct prb_entry *e; - unsigned long head; - unsigned long res; -@@ -175,6 +177,7 @@ void prb_commit(struct prb_handle *h) - } - e->seq = ++rb->seq; - head += e->size; -+ changed = true; - } - atomic_long_set_release(&rb->head, res); - atomic_dec(&rb->ctx); -@@ -185,6 +188,18 @@ void prb_commit(struct prb_handle *h) - } - - prb_unlock(rb->cpulock, h->cpu); -+ -+ if (changed) { -+ atomic_long_inc(&rb->wq_counter); -+ if (wq_has_sleeper(rb->wq)) { -+#ifdef CONFIG_IRQ_WORK -+ irq_work_queue(rb->wq_work); -+#else -+ if (!in_nmi()) -+ wake_up_interruptible_all(rb->wq); -+#endif -+ } -+ } - } - - /* -@@ -437,3 +452,43 @@ int prb_iter_next(struct prb_iterator *i - - return 1; - } -+ -+/* -+ * prb_iter_wait_next: Advance to the next record, blocking if none available. -+ * @iter: Iterator tracking the current position. -+ * @buf: A buffer to store the data of the next record. May be NULL. -+ * @size: The size of @buf. (Ignored if @buf is NULL.) -+ * @seq: The sequence number of the next record. May be NULL. -+ * -+ * If a next record is already available, this function works like -+ * prb_iter_next(). Otherwise block interruptible until a next record is -+ * available. -+ * -+ * When a next record is available, @iter is advanced and (if specified) -+ * the data and/or sequence number of that record are provided. -+ * -+ * This function might sleep. -+ * -+ * Returns 1 if @iter was advanced, -EINVAL if @iter is now invalid, or -+ * -ERESTARTSYS if interrupted by a signal. -+ */ -+int prb_iter_wait_next(struct prb_iterator *iter, char *buf, int size, u64 *seq) -+{ -+ unsigned long last_seen; -+ int ret; -+ -+ for (;;) { -+ last_seen = atomic_long_read(&iter->rb->wq_counter); -+ -+ ret = prb_iter_next(iter, buf, size, seq); -+ if (ret != 0) -+ break; -+ -+ ret = wait_event_interruptible(*iter->rb->wq, -+ last_seen != atomic_long_read(&iter->rb->wq_counter)); -+ if (ret < 0) -+ break; -+ } -+ -+ return ret; -+} |