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Subject[tip: irq/urgent] genirq: Prevent [devm_]irq_alloc_desc from returning irq 0
The following commit has been merged into the irq/urgent branch of tip:

Commit-ID: 4c7bcb51ae25f79e3733982e5d0cd8ce8640ddfc
Gitweb: https://git.kernel.org/tip/4c7bcb51ae25f79e3733982e5d0cd8ce8640ddfc
Author: Hans de Goede <hdegoede@redhat.com>
AuthorDate: Mon, 21 Dec 2020 19:56:47 +01:00
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Fri, 05 Feb 2021 20:48:28 +01:00

genirq: Prevent [devm_]irq_alloc_desc from returning irq 0

Since commit a85a6c86c25b ("driver core: platform: Clarify that IRQ 0
is invalid"), having a linux-irq with number 0 will trigger a WARN()
when calling platform_get_irq*() to retrieve that linux-irq.

Since [devm_]irq_alloc_desc allocs a single irq and since irq 0 is not used
on some systems, it can return 0, triggering that WARN(). This happens
e.g. on Intel Bay Trail and Cherry Trail devices using the LPE audio engine
for HDMI audio:

0 is an invalid IRQ number
WARNING: CPU: 3 PID: 472 at drivers/base/platform.c:238 platform_get_irq_optional+0x108/0x180
Modules linked in: snd_hdmi_lpe_audio(+) ...

Call Trace:
platform_get_irq+0x17/0x30
hdmi_lpe_audio_probe+0x4a/0x6c0 [snd_hdmi_lpe_audio]

---[ end trace ceece38854223a0b ]---

Change the 'from' parameter passed to __[devm_]irq_alloc_descs() by the
[devm_]irq_alloc_desc macros from 0 to 1, so that these macros will no
longer return 0.

Fixes: a85a6c86c25b ("driver core: platform: Clarify that IRQ 0 is invalid")
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20201221185647.226146-1-hdegoede@redhat.com
---
include/linux/irq.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/irq.h b/include/linux/irq.h
index 4aeb1c4..2efde6a 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -928,7 +928,7 @@ int __devm_irq_alloc_descs(struct device *dev, int irq, unsigned int from,
__irq_alloc_descs(irq, from, cnt, node, THIS_MODULE, NULL)

#define irq_alloc_desc(node) \
- irq_alloc_descs(-1, 0, 1, node)
+ irq_alloc_descs(-1, 1, 1, node)

#define irq_alloc_desc_at(at, node) \
irq_alloc_descs(at, at, 1, node)
@@ -943,7 +943,7 @@ int __devm_irq_alloc_descs(struct device *dev, int irq, unsigned int from,
__devm_irq_alloc_descs(dev, irq, from, cnt, node, THIS_MODULE, NULL)

#define devm_irq_alloc_desc(dev, node) \
- devm_irq_alloc_descs(dev, -1, 0, 1, node)
+ devm_irq_alloc_descs(dev, -1, 1, 1, node)

#define devm_irq_alloc_desc_at(dev, at, node) \
devm_irq_alloc_descs(dev, at, at, 1, node)
\
 
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