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path: root/drivers/s390/scsi/zfcp_diag.c
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// SPDX-License-Identifier: GPL-2.0
/*
 * zfcp device driver
 *
 * Functions to handle diagnostics.
 *
 * Copyright IBM Corp. 2018
 */

#include <linux/spinlock.h>
#include <linux/jiffies.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/slab.h>

#include "zfcp_diag.h"
#include "zfcp_ext.h"
#include "zfcp_def.h"

/* Max age of data in a diagnostics buffer before it needs a refresh (in ms). */
#define ZFCP_DIAG_MAX_AGE (5 * 1000)

/**
 * zfcp_diag_adapter_setup() - Setup storage for adapter diagnostics.
 * @adapter: the adapter to setup diagnostics for.
 *
 * Creates the data-structures to store the diagnostics for an adapter. This
 * overwrites whatever was stored before at &zfcp_adapter->diagnostics!
 *
 * Return:
 * * 0	     - Everyting is OK
 * * -ENOMEM - Could not allocate all/parts of the data-structures;
 *	       &zfcp_adapter->diagnostics remains unchanged
 */
int zfcp_diag_adapter_setup(struct zfcp_adapter *const adapter)
{
	struct zfcp_diag_adapter *diag;
	struct zfcp_diag_header *hdr;

	diag = kzalloc(sizeof(*diag), GFP_KERNEL);
	if (diag == NULL)
		return -ENOMEM;

	/* setup header for port_data */
	hdr = &diag->port_data.header;

	spin_lock_init(&hdr->access_lock);
	hdr->buffer = &diag->port_data.data;
	hdr->buffer_size = sizeof(diag->port_data.data);
	/* set the timestamp so that the first test on age will always fail */
	hdr->timestamp = jiffies - msecs_to_jiffies(ZFCP_DIAG_MAX_AGE);

	adapter->diagnostics = diag;
	return 0;
}

/**
 * zfcp_diag_adapter_free() - Frees all adapter diagnostics allocations.
 * @adapter: the adapter whose diagnostic structures should be freed.
 *
 * Frees all data-structures in the given adapter that store diagnostics
 * information. Can savely be called with partially setup diagnostics.
 */
void zfcp_diag_adapter_free(struct zfcp_adapter *const adapter)
{
	kfree(adapter->diagnostics);
	adapter->diagnostics = NULL;
}

/**
 * zfcp_diag_update_xdata() - Update a diagnostics buffer.
 * @hdr: the meta data to update.
 * @data: data to use for the update.
 * @incomplete: flag stating whether the data in @data is incomplete.
 */
void zfcp_diag_update_xdata(struct zfcp_diag_header *const hdr,
			    const void *const data, const bool incomplete)
{
	const unsigned long capture_timestamp = jiffies;
	unsigned long flags;

	spin_lock_irqsave(&hdr->access_lock, flags);

	/* make sure we never go into the past with an update */
	if (!time_after_eq(capture_timestamp, hdr->timestamp))
		goto out;

	hdr->timestamp = capture_timestamp;
	hdr->incomplete = incomplete;
	memcpy(hdr->buffer, data, hdr->buffer_size);
out:
	spin_unlock_irqrestore(&hdr->access_lock, flags);
}