[PATCH] alpha: marvel: Fix lock ordering in init_io7_irqs()

Matt Turner posted 1 patch 3 days, 19 hours ago
arch/alpha/kernel/sys_marvel.c | 27 +++++++++++++--------------
1 file changed, 13 insertions(+), 14 deletions(-)
[PATCH] alpha: marvel: Fix lock ordering in init_io7_irqs()
Posted by Matt Turner 3 days, 19 hours ago
Move irq_set_chip_and_handler() and irq_set_status_flags() calls
outside the io7->irq_lock raw spinlock.  These functions take
sparse_irq_lock, which is a mutex, and taking a sleeping lock while
holding a raw spinlock is invalid.  The raw spinlock only needs to
protect the hardware CSR accesses.

This fixes the following lockdep splat during boot:

  [ BUG: Invalid wait context ]
  swapper/0/0 is trying to lock:
  sparse_irq_lock{....}-{4:4}, at: irq_mark_irq
  other info that might help us debug this:
  context-{5:5}
  1 lock held by swapper/0/0:
   #0: &io7->irq_lock{....}-{2:2}, at: init_io7_irqs.constprop.0

Assisted-by: Claude:claude-opus-4-6
Signed-off-by: Matt Turner <mattst88@gmail.com>
---
 arch/alpha/kernel/sys_marvel.c | 27 +++++++++++++--------------
 1 file changed, 13 insertions(+), 14 deletions(-)

diff --git ./arch/alpha/kernel/sys_marvel.c ./arch/alpha/kernel/sys_marvel.c
index 1f99b03effc2..d0bdd5e6cfd7 100644
--- ./arch/alpha/kernel/sys_marvel.c
+++ ./arch/alpha/kernel/sys_marvel.c
@@ -263,6 +263,18 @@ init_io7_irqs(struct io7 *io7,
 	 */
 	printk("  Interrupts reported to CPU at PE %u\n", boot_cpuid);
 
+	/* Set up the lsi irqs.  */
+	for (i = 0; i < 128; ++i) {
+		irq_set_chip_and_handler(base + i, lsi_ops, handle_level_irq);
+		irq_set_status_flags(i, IRQ_LEVEL);
+	}
+
+	/* Set up the msi irqs.  */
+	for (i = 128; i < (128 + 512); ++i) {
+		irq_set_chip_and_handler(base + i, msi_ops, handle_level_irq);
+		irq_set_status_flags(i, IRQ_LEVEL);
+	}
+
 	raw_spin_lock(&io7->irq_lock);
 
 	/* set up the error irqs */
@@ -272,26 +284,13 @@ init_io7_irqs(struct io7 *io7,
 	io7_redirect_irq(io7, &io7->csrs->STV_CTL.csr, boot_cpuid);
 	io7_redirect_irq(io7, &io7->csrs->HEI_CTL.csr, boot_cpuid);
 
-	/* Set up the lsi irqs.  */
-	for (i = 0; i < 128; ++i) {
-		irq_set_chip_and_handler(base + i, lsi_ops, handle_level_irq);
-		irq_set_status_flags(i, IRQ_LEVEL);
-	}
-
 	/* Disable the implemented irqs in hardware.  */
-	for (i = 0; i < 0x60; ++i) 
+	for (i = 0; i < 0x60; ++i)
 		init_one_io7_lsi(io7, i, boot_cpuid);
 
 	init_one_io7_lsi(io7, 0x74, boot_cpuid);
 	init_one_io7_lsi(io7, 0x75, boot_cpuid);
 
-
-	/* Set up the msi irqs.  */
-	for (i = 128; i < (128 + 512); ++i) {
-		irq_set_chip_and_handler(base + i, msi_ops, handle_level_irq);
-		irq_set_status_flags(i, IRQ_LEVEL);
-	}
-
 	for (i = 0; i < 16; ++i)
 		init_one_io7_msi(io7, i, boot_cpuid);
 
-- 
2.52.0