Re: [PATCH v2 6/8] remoteproc: Introduce "panic" callback in ops

[Mathieu Poirier]

On Thu, Dec 26, 2019 at 09:32:13PM -0800, Bjorn Andersson wrote:
> Introduce a "panic" function in the remoteproc ops table, to allow
> remoteproc instances to perform operations needed in order to aid in
> post mortem system debugging, such as flushing caches etc, when the
> kernel panics.
> 
> Signed-off-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>
> ---
> 
> Changes since v1:
> - None
> 
>  drivers/remoteproc/remoteproc_core.c | 17 +++++++++++++++++
>  include/linux/remoteproc.h           |  4 ++++
>  2 files changed, 21 insertions(+)
> 
> diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
> index 307df98347ba..779f19d6d8e7 100644
> --- a/drivers/remoteproc/remoteproc_core.c
> +++ b/drivers/remoteproc/remoteproc_core.c
> @@ -1832,6 +1832,17 @@ void rproc_shutdown(struct rproc *rproc)
>  }
>  EXPORT_SYMBOL(rproc_shutdown);
>  
> +static int rproc_panic_handler(struct notifier_block *nb, unsigned long event,
> +			       void *ptr)
> +{
> +	struct rproc *rproc = container_of(nb, struct rproc, panic_nb);
> +
> +	if (rproc->state == RPROC_RUNNING)
> +		rproc->ops->panic(rproc);
> +
> +	return NOTIFY_DONE;
> +}
> +
>  /**
>   * rproc_get_by_phandle() - find a remote processor by phandle
>   * @phandle: phandle to the rproc
> @@ -2057,6 +2068,12 @@ struct rproc *rproc_alloc(struct device *dev, const char *name,
>  		rproc->ops->get_boot_addr = rproc_elf_get_boot_addr;
>  	}
>  
> +	/* Register panic notifier for remoteprocs with "panic" callback */
> +	if (rproc->ops->panic) {
> +		rproc->panic_nb.notifier_call = rproc_panic_handler;
> +		atomic_notifier_chain_register(&panic_notifier_list, &rproc->panic_nb);

Line over 80 characters.

> +	}
> +
>  	mutex_init(&rproc->lock);
>  
>  	idr_init(&rproc->notifyids);
> diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
> index 16ad66683ad0..7836c528d309 100644
> --- a/include/linux/remoteproc.h
> +++ b/include/linux/remoteproc.h
> @@ -369,6 +369,7 @@ enum rsc_handling_status {
>   *			expects to find it
>   * @sanity_check:	sanity check the fw image
>   * @get_boot_addr:	get boot address to entry point specified in firmware
> + * @panic:	optional callback to react to system panic
>   */
>  struct rproc_ops {
>  	int (*start)(struct rproc *rproc);
> @@ -383,6 +384,7 @@ struct rproc_ops {
>  	int (*load)(struct rproc *rproc, const struct firmware *fw);
>  	int (*sanity_check)(struct rproc *rproc, const struct firmware *fw);
>  	u32 (*get_boot_addr)(struct rproc *rproc, const struct firmware *fw);
> +	void (*panic)(struct rproc *rproc);
>  };
>  
>  /**
> @@ -481,6 +483,7 @@ struct rproc_dump_segment {
>   * @auto_boot: flag to indicate if remote processor should be auto-started
>   * @dump_segments: list of segments in the firmware
>   * @nb_vdev: number of vdev currently handled by rproc
> + * @panic_nb: notifier_block for remoteproc's panic handler
>   */
>  struct rproc {
>  	struct list_head node;
> @@ -514,6 +517,7 @@ struct rproc {
>  	bool auto_boot;
>  	struct list_head dump_segments;
>  	int nb_vdev;
> +	struct notifier_block panic_nb;
>  };
>  
>  /**
> -- 
> 2.24.0
>