linux-kernel - Re: [PATCH v3 6/7] ocxl: move event

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Date:   Mon, 25 Mar 2019 16:41:34 +0100
From:   Frederic Barrat <fbarrat@...ux.ibm.com>
To:     "Alastair D'Silva" <alastair@....ibm.com>, alastair@...ilva.org
Cc:     Andrew Donnellan <andrew.donnellan@....ibm.com>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH v3 6/7] ocxl: move event_fd handling to frontend



Le 25/03/2019 à 06:44, Alastair D'Silva a écrit :
> From: Alastair D'Silva <alastair@...ilva.org>
> 
> Event_fd is only used in the driver frontend, so it does not
> need to exist in the backend code. Relocate it to the frontend
> and provide an opaque mechanism for consumers instead.
> 
> Signed-off-by: Alastair D'Silva <alastair@...ilva.org>
> ---
>   drivers/misc/ocxl/afu_irq.c       | 76 ++++++++++++++++++-------------
>   drivers/misc/ocxl/file.c          | 22 ++++++++-
>   drivers/misc/ocxl/ocxl_internal.h |  5 --
>   include/misc/ocxl.h               | 46 +++++++++++++++++++
>   4 files changed, 111 insertions(+), 38 deletions(-)
> 
> diff --git a/drivers/misc/ocxl/afu_irq.c b/drivers/misc/ocxl/afu_irq.c
> index 2d410cd6f817..d71e62df7d31 100644
> --- a/drivers/misc/ocxl/afu_irq.c
> +++ b/drivers/misc/ocxl/afu_irq.c
> @@ -1,7 +1,7 @@
>   // SPDX-License-Identifier: GPL-2.0+
>   // Copyright 2017 IBM Corp.
>   #include <linux/interrupt.h>
> -#include <linux/eventfd.h>
> +#include <asm/pnv-ocxl.h>
>   #include "ocxl_internal.h"
>   #include "trace.h"
>   
> @@ -11,7 +11,9 @@ struct afu_irq {
>   	unsigned int virq;
>   	char *name;
>   	u64 trigger_page;
> -	struct eventfd_ctx *ev_ctx;
> +	irqreturn_t (*handler)(void *private);
> +	void (*free_private)(void *private);
> +	void *private;
>   };
>   
>   int ocxl_irq_offset_to_id(struct ocxl_context *ctx, u64 offset)
> @@ -24,14 +26,43 @@ u64 ocxl_irq_id_to_offset(struct ocxl_context *ctx, int irq_id)
>   	return ctx->afu->irq_base_offset + (irq_id << PAGE_SHIFT);
>   }
>   
> +int ocxl_irq_set_handler(struct ocxl_context *ctx, int irq_id,
> +		irqreturn_t (*handler)(void *private),
> +		void (*free_private)(void *private),
> +		void *private)
> +{
> +	struct afu_irq *irq;
> +	int rc;
> +
> +	mutex_lock(&ctx->irq_lock);
> +	irq = idr_find(&ctx->irq_idr, irq_id);
> +	if (!irq) {
> +		rc = -EINVAL;
> +		goto unlock;
> +	}
> +
> +	irq->handler = handler;
> +	irq->private = private;
> +
> +	rc = 0;
> +	goto unlock;


That goto is too much.


> +
> +unlock:
> +	mutex_unlock(&ctx->irq_lock);
> +	return rc;
> +}
> +EXPORT_SYMBOL_GPL(ocxl_irq_set_handler);
> +
>   static irqreturn_t afu_irq_handler(int virq, void *data)
>   {
>   	struct afu_irq *irq = (struct afu_irq *) data;
>   
>   	trace_ocxl_afu_irq_receive(virq);
> -	if (irq->ev_ctx)
> -		eventfd_signal(irq->ev_ctx, 1);
> -	return IRQ_HANDLED;
> +
> +	if (irq->handler)
> +		return irq->handler(irq->private);
> +
> +	return IRQ_HANDLED; // Just drop it on the ground
>   }
>   
>   static int setup_afu_irq(struct ocxl_context *ctx, struct afu_irq *irq)
> @@ -118,6 +149,8 @@ int ocxl_afu_irq_alloc(struct ocxl_context *ctx, int *irq_id)
>   	return rc;
>   }
>   
> +EXPORT_SYMBOL_GPL(ocxl_afu_irq_alloc);


nit: checkpatch doesn't like the empty line between the function and its 
symbol export. Also true for a few other symbols in that file.



> diff --git a/include/misc/ocxl.h b/include/misc/ocxl.h
> index a8fe0ce4ea67..1b48e9d63abb 100644
> --- a/include/misc/ocxl.h
> +++ b/include/misc/ocxl.h
> @@ -161,6 +161,52 @@ int ocxl_context_attach(struct ocxl_context *ctx, u64 amr,
>    */
>   int ocxl_context_detach(struct ocxl_context *ctx);
>   
> +// AFU IRQs
> +
> +/**
> + * Allocate an IRQ associated with an AFU context
> + * @ctx: the AFU context
> + * @irq_id: out, the IRQ ID
> + *
> + * Returns 0 on success, negative on failure
> + */
> +extern int ocxl_afu_irq_alloc(struct ocxl_context *ctx, int *irq_id);
> +
> +/**
> + * Frees an IRQ associated with an AFU context
> + * @ctx: the AFU context
> + * @irq_id: the IRQ ID
> + *
> + * Returns 0 on success, negative on failure
> + */
> +extern int ocxl_afu_irq_free(struct ocxl_context *ctx, int irq_id);
> +
> +/**
> + * Gets the address of the trigger page for an IRQ
> + * This can then be provided to an AFU which will write to that
> + * page to trigger the IRQ.
> + * @ctx: The AFU context that the IRQ is associated with
> + * @irq_id: The IRQ ID
> + *
> + * returns the trigger page address, or 0 if the IRQ is not valid
> + */
> +extern u64 ocxl_afu_irq_get_addr(struct ocxl_context *ctx, int irq_id);
> +
> +/**
> + * Provide a callback to be called when an IRQ is triggered
> + * @ctx: The AFU context that the IRQ is associated with
> + * @irq_id: The IRQ ID
> + * @handler: the callback to be called when the IRQ is triggered
> + * @free_private: the callback to be called when the IRQ is freed

We should mention free_private can be NULL, in which case it is ignored.

   Fred