cxl: Fix NULL pointer dereference on kernel contexts with no AFU interrupts

If a kernel context is initialised and does not have any AFU interrupts
allocated it will cause a NULL pointer dereference when the context is
detached since the irq_names list will not have been initialised.

Move the initialisation of the irq_names list into the cxl_context_init
routine so that it will be valid for the entire lifetime of the context
and will not cause a NULL pointer dereference.

Signed-off-by: Ian Munsie <imunsie@au1.ibm.com>
Reviewed-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

drivers/misc/cxl/context.c

@@ -67,6 +67,8 @@ int cxl_context_init(struct cxl_context *ctx, struct cxl_afu *afu, bool master,
 	ctx->pending_fault = false;
 	ctx->pending_afu_err = false;
 
+	INIT_LIST_HEAD(&ctx->irq_names);
+
 	/*
 	 * When we have to destroy all contexts in cxl_context_detach_all() we
 	 * end up with afu_release_irqs() called from inside a

drivers/misc/cxl/irq.c

@@ -260,9 +260,6 @@ int afu_allocate_irqs(struct cxl_context *ctx, u32 count)
 	else
 		alloc_count = count + 1;
 
-	/* Initialize the list head to hold irq names */
-	INIT_LIST_HEAD(&ctx->irq_names);
-
 	if ((rc = cxl_ops->alloc_irq_ranges(&ctx->irqs, ctx->afu->adapter,
 							alloc_count)))
 		return rc;