linux-kernel - [PATCH] MIPS: cevt-r4k: Don't call get_c0_compare

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Message-Id: <20240813-get_c0_compare_int-v1-1-a0a1b007d736@flygoat.com>
Date: Tue, 13 Aug 2024 10:59:08 +0100
From: Jiaxun Yang <jiaxun.yang@...goat.com>
To: Thomas Bogendoerfer <tsbogend@...ha.franken.de>
Cc: linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Serge Semin <fancer.lancer@...il.com>, 
 Jiaxun Yang <jiaxun.yang@...goat.com>
Subject: [PATCH] MIPS: cevt-r4k: Don't call get_c0_compare_int if timer irq
 is installed

This avoids warning:

[    0.118053] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:283

Caused by get_c0_compare_int on secondary CPU.

We also skipped saving IRQ number to struct clock_event_device *cd as
it's never used by clockevent core, as per comments it's only meant
for "non CPU local devices".

Reported-by: Serge Semin <fancer.lancer@...il.com>
Closes: https://lore.kernel.org/linux-mips/6szkkqxpsw26zajwysdrwplpjvhl5abpnmxgu2xuj3dkzjnvsf@4daqrz4mf44k/
Signed-off-by: Jiaxun Yang <jiaxun.yang@...goat.com>
---
 arch/mips/kernel/cevt-r4k.c | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/arch/mips/kernel/cevt-r4k.c b/arch/mips/kernel/cevt-r4k.c
index 368e8475870f..5f6e9e2ebbdb 100644
--- a/arch/mips/kernel/cevt-r4k.c
+++ b/arch/mips/kernel/cevt-r4k.c
@@ -303,13 +303,6 @@ int r4k_clockevent_init(void)
 	if (!c0_compare_int_usable())
 		return -ENXIO;
 
-	/*
-	 * With vectored interrupts things are getting platform specific.
-	 * get_c0_compare_int is a hook to allow a platform to return the
-	 * interrupt number of its liking.
-	 */
-	irq = get_c0_compare_int();
-
 	cd = &per_cpu(mips_clockevent_device, cpu);
 
 	cd->name		= "MIPS";
@@ -320,7 +313,6 @@ int r4k_clockevent_init(void)
 	min_delta		= calculate_min_delta();
 
 	cd->rating		= 300;
-	cd->irq			= irq;
 	cd->cpumask		= cpumask_of(cpu);
 	cd->set_next_event	= mips_next_event;
 	cd->event_handler	= mips_event_handler;
@@ -332,6 +324,13 @@ int r4k_clockevent_init(void)
 
 	cp0_timer_irq_installed = 1;
 
+	/*
+	 * With vectored interrupts things are getting platform specific.
+	 * get_c0_compare_int is a hook to allow a platform to return the
+	 * interrupt number of its liking.
+	 */
+	irq = get_c0_compare_int();
+
 	if (request_irq(irq, c0_compare_interrupt, flags, "timer",
 			c0_compare_interrupt))
 		pr_err("Failed to request irq %d (timer)\n", irq);

---
base-commit: 9e6869691724b12e1f43655eeedc35fade38120c
change-id: 20240812-get_c0_compare_int-66935853a308

Best regards,
-- 
Jiaxun Yang <jiaxun.yang@...goat.com>