Re: [PATCH v2 3/3] remoteproc: pru: Fix and cleanup firmware interrupt mapping logic

[Mathieu Poirier <mathieu.poirier@linaro.org>]

On Wed, Apr 07, 2021 at 10:56:41AM -0500, Suman Anna wrote:
> The PRU firmware interrupt mappings are configured and unconfigured in
> .start() and .stop() callbacks respectively using the variables 'evt_count'
> and a 'mapped_irq' pointer. These variables are modified only during these
> callbacks but are not re-initialized/reset properly during unwind or
> failure paths. These stale values caused a kernel crash while stopping a
> PRU remoteproc running a different firmware with no events on a subsequent
> run after a previous run that was running a firmware with events.
> 
> Fix this crash by ensuring that the evt_count is 0 and the mapped_irq
> pointer is set to NULL in pru_dispose_irq_mapping(). Also, reset these
> variables properly during any failures in the .start() callback. While
> at this, the pru_dispose_irq_mapping() callsites are all made to look
> the same, moving any conditional logic to inside the function.
> 
> Fixes: c75c9fdac66e ("remoteproc: pru: Add support for PRU specific interrupt configuration")
> Reported-by: Vignesh Raghavendra <vigneshr@ti.com>
> Signed-off-by: Suman Anna <s-anna@ti.com>
> ---
> v2:
>  - Fixed two additional cleanup paths in pru_handle_intrmap()
>    addressing Mathieu's review comment
> v1: https://patchwork.kernel.org/project/linux-remoteproc/patch/20210323223839.17464-4-s-anna@ti.com/
> 
>  drivers/remoteproc/pru_rproc.c | 22 +++++++++++++++++-----
>  1 file changed, 17 insertions(+), 5 deletions(-)
>

Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
 
> diff --git a/drivers/remoteproc/pru_rproc.c b/drivers/remoteproc/pru_rproc.c
> index 87b43976c51b..04863bf23db8 100644
> --- a/drivers/remoteproc/pru_rproc.c
> +++ b/drivers/remoteproc/pru_rproc.c
> @@ -266,12 +266,17 @@ static void pru_rproc_create_debug_entries(struct rproc *rproc)
>  
>  static void pru_dispose_irq_mapping(struct pru_rproc *pru)
>  {
> -	while (pru->evt_count--) {
> +	if (!pru->mapped_irq)
> +		return;
> +
> +	while (pru->evt_count) {
> +		pru->evt_count--;
>  		if (pru->mapped_irq[pru->evt_count] > 0)
>  			irq_dispose_mapping(pru->mapped_irq[pru->evt_count]);
>  	}
>  
>  	kfree(pru->mapped_irq);
> +	pru->mapped_irq = NULL;
>  }
>  
>  /*
> @@ -307,8 +312,10 @@ static int pru_handle_intrmap(struct rproc *rproc)
>  	pru->evt_count = rsc->num_evts;
>  	pru->mapped_irq = kcalloc(pru->evt_count, sizeof(unsigned int),
>  				  GFP_KERNEL);
> -	if (!pru->mapped_irq)
> +	if (!pru->mapped_irq) {
> +		pru->evt_count = 0;
>  		return -ENOMEM;
> +	}
>  
>  	/*
>  	 * parse and fill in system event to interrupt channel and
> @@ -317,13 +324,19 @@ static int pru_handle_intrmap(struct rproc *rproc)
>  	 * corresponding sibling PRUSS INTC node.
>  	 */
>  	parent = of_get_parent(dev_of_node(pru->dev));
> -	if (!parent)
> +	if (!parent) {
> +		kfree(pru->mapped_irq);
> +		pru->mapped_irq = NULL;
> +		pru->evt_count = 0;
>  		return -ENODEV;
> +	}
>  
>  	irq_parent = of_get_child_by_name(parent, "interrupt-controller");
>  	of_node_put(parent);
>  	if (!irq_parent) {
>  		kfree(pru->mapped_irq);
> +		pru->mapped_irq = NULL;
> +		pru->evt_count = 0;
>  		return -ENODEV;
>  	}
>  
> @@ -398,8 +411,7 @@ static int pru_rproc_stop(struct rproc *rproc)
>  	pru_control_write_reg(pru, PRU_CTRL_CTRL, val);
>  
>  	/* dispose irq mapping - new firmware can provide new mapping */
> -	if (pru->mapped_irq)
> -		pru_dispose_irq_mapping(pru);
> +	pru_dispose_irq_mapping(pru);
>  
>  	return 0;
>  }
> -- 
> 2.30.1
>