99 lines
2.8 KiB
Diff
99 lines
2.8 KiB
Diff
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From f717642e336564e1ee6e240dcfe20451242a2931 Mon Sep 17 00:00:00 2001
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From: Thomas Gleixner <tglx@linutronix.de>
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Date: Wed, 19 Sep 2012 14:50:37 +0200
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Subject: [PATCH 245/365] printk: Make rt aware
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X-NVConfidentiality: public
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Drop the lock before calling the console driver and do not disable
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interrupts while printing to a serial console.
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Change-Id: I88d565b2b1b7a631cc02d97074681f5c2e9cd9a4
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Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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---
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kernel/printk/printk.c | 24 +++++++++++++++++++++++-
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1 file changed, 23 insertions(+), 1 deletion(-)
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diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
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index 68b7e06..32c45a5 100644
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--- a/kernel/printk/printk.c
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+++ b/kernel/printk/printk.c
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@@ -1585,6 +1585,7 @@ static void call_console_drivers(int level,
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if (!console_drivers)
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return;
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+ migrate_disable();
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for_each_console(con) {
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if (exclusive_console && con != exclusive_console)
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continue;
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@@ -1600,6 +1601,7 @@ static void call_console_drivers(int level,
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else
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con->write(con, text, len);
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}
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+ migrate_enable();
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}
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int printk_delay_msec __read_mostly;
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@@ -1895,12 +1897,22 @@ asmlinkage int vprintk_emit(int facility, int level,
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/* If called from the scheduler, we can not call up(). */
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if (!in_sched) {
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+ int may_trylock = 1;
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+
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+#ifdef CONFIG_PREEMPT_RT_FULL
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+ /*
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+ * we can't take a sleeping lock with IRQs or preeption disabled
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+ * so we can't print in these contexts
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+ */
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+ if (!(preempt_count() == 0 && !irqs_disabled()))
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+ may_trylock = 0;
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+#endif
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/*
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* Try to acquire and then immediately release the console
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* semaphore. The release will print out buffers and wake up
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* /dev/kmsg and syslog() users.
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*/
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- if (console_trylock())
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+ if (may_trylock && console_trylock())
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console_unlock();
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}
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@@ -2286,11 +2298,16 @@ static void console_cont_flush(char *text, size_t size)
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goto out;
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len = cont_print_text(text, size);
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+#ifdef CONFIG_PREEMPT_RT_FULL
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+ raw_spin_unlock_irqrestore(&logbuf_lock, flags);
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+ call_console_drivers(cont.level, NULL, 0, text, len);
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+#else
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raw_spin_unlock(&logbuf_lock);
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stop_critical_timings();
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call_console_drivers(cont.level, NULL, 0, text, len);
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start_critical_timings();
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local_irq_restore(flags);
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+#endif
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return;
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out:
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raw_spin_unlock_irqrestore(&logbuf_lock, flags);
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@@ -2415,6 +2432,10 @@ void console_unlock(void)
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}
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console_idx = log_next(console_idx);
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console_seq++;
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+#ifdef CONFIG_PREEMPT_RT_FULL
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+ raw_spin_unlock_irqrestore(&logbuf_lock, flags);
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+ call_console_drivers(level, ext_text, ext_len, text, len);
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+#else
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raw_spin_unlock(&logbuf_lock);
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stop_critical_timings(); /* don't trace print latency */
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@@ -2422,6 +2443,7 @@ void console_unlock(void)
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start_critical_timings();
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printk_safe_exit_irqrestore(flags);
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+#endif
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if (do_cond_resched)
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cond_resched();
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}
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--
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2.28.0
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