ARM: s3c: irq-s3c24xx: Fix return value check for s3c24xx_init_intc()

[ Upstream commit 2aa717473ce96c93ae43a5dc8c23cedc8ce7dd9f ]

The s3c24xx_init_intc() returns an error pointer upon failure, not NULL.
let's add an error pointer check in s3c24xx_handle_irq.

s3c_intc[0] is not NULL or ERR, we can simplify the code.

Fixes: 1f629b7a3ced ("ARM: S3C24XX: transform irq handling into a declarative form")
Signed-off-by: Jackie Liu <liuyun01@kylinos.cn>
Link: https://lore.kernel.org/r/20210901123557.1043953-1-liu.yun@linux.dev
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/arch/arm/mach-s3c/irq-s3c24xx.c b/arch/arm/mach-s3c/irq-s3c24xx.c
index 3edc5f614eefc4f704dbdfc5658dd62ee55793d5..c1c2f041ad3b108a24e07960accf41f864e68394 100644 (file)
--- a/arch/arm/mach-s3c/irq-s3c24xx.c
+++ b/arch/arm/mach-s3c/irq-s3c24xx.c
@@ -361,11 +361,25 @@ static inline int s3c24xx_handle_intc(struct s3c_irq_intc *intc,
 static asmlinkage void __exception_irq_entry s3c24xx_handle_irq(struct pt_regs *regs)
 {
        do {
-               if (likely(s3c_intc[0]))
-                       if (s3c24xx_handle_intc(s3c_intc[0], regs, 0))
-                               continue;
+               /*
+                * For platform based machines, neither ERR nor NULL can happen here.
+                * The s3c24xx_handle_irq() will be set as IRQ handler iff this succeeds:
+                *
+                *    s3c_intc[0] = s3c24xx_init_intc()
+                *
+                * If this fails, the next calls to s3c24xx_init_intc() won't be executed.
+                *
+                * For DT machine, s3c_init_intc_of() could set the IRQ handler without
+                * setting s3c_intc[0] only if it was called with num_ctrl=0. There is no
+                * such code path, so again the s3c_intc[0] will have a valid pointer if
+                * set_handle_irq() is called.
+                *
+                * Therefore in s3c24xx_handle_irq(), the s3c_intc[0] is always something.
+                */
+               if (s3c24xx_handle_intc(s3c_intc[0], regs, 0))
+                       continue;
 
-               if (s3c_intc[2])
+               if (!IS_ERR_OR_NULL(s3c_intc[2]))
                        if (s3c24xx_handle_intc(s3c_intc[2], regs, 64))
                                continue;