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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"
static DECLARE_WAIT_QUEUE_HEAD(__zfcp_diag_publish_wait);
/**
* 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;
diag->max_age = (5 * 1000); /* default value: 5 s */
/* 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(diag->max_age);
/* setup header for config_data */
hdr = &diag->config_data.header;
spin_lock_init(&hdr->access_lock);
hdr->buffer = &diag->config_data.data;
hdr->buffer_size = sizeof(diag->config_data.data);
/* set the timestamp so that the first test on age will always fail */
hdr->timestamp = jiffies - msecs_to_jiffies(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);
}
/**
* zfcp_diag_update_port_data_buffer() - Implementation of
* &typedef zfcp_diag_update_buffer_func
* to collect and update Port Data.
* @adapter: Adapter to collect Port Data from.
*
* This call is SYNCHRONOUS ! It blocks till the respective command has
* finished completely, or has failed in some way.
*
* Return:
* * 0 - Successfully retrieved new Diagnostics and Updated the buffer;
* this also includes cases where data was retrieved, but
* incomplete; you'll have to check the flag ``incomplete``
* of &struct zfcp_diag_header.
* * see zfcp_fsf_exchange_port_data_sync() for possible error-codes (
* excluding -EAGAIN)
*/
int zfcp_diag_update_port_data_buffer(struct zfcp_adapter *const adapter)
{
int rc;
rc = zfcp_fsf_exchange_port_data_sync(adapter->qdio, NULL);
if (rc == -EAGAIN)
rc = 0; /* signaling incomplete via struct zfcp_diag_header */
/* buffer-data was updated in zfcp_fsf_exchange_port_data_handler() */
return rc;
}
/**
* zfcp_diag_update_config_data_buffer() - Implementation of
* &typedef zfcp_diag_update_buffer_func
* to collect and update Config Data.
* @adapter: Adapter to collect Config Data from.
*
* This call is SYNCHRONOUS ! It blocks till the respective command has
* finished completely, or has failed in some way.
*
* Return:
* * 0 - Successfully retrieved new Diagnostics and Updated the buffer;
* this also includes cases where data was retrieved, but
* incomplete; you'll have to check the flag ``incomplete``
* of &struct zfcp_diag_header.
* * see zfcp_fsf_exchange_config_data_sync() for possible error-codes (
* excluding -EAGAIN)
*/
int zfcp_diag_update_config_data_buffer(struct zfcp_adapter *const adapter)
{
int rc;
rc = zfcp_fsf_exchange_config_data_sync(adapter->qdio, NULL);
if (rc == -EAGAIN)
rc = 0; /* signaling incomplete via struct zfcp_diag_header */
/* buffer-data was updated in zfcp_fsf_exchange_config_data_handler() */
return rc;
}
static int __zfcp_diag_update_buffer(struct zfcp_adapter *const adapter,
struct zfcp_diag_header *const hdr,
zfcp_diag_update_buffer_func buffer_update,
unsigned long *const flags)
__must_hold(hdr->access_lock)
{
int rc;
if (hdr->updating == 1) {
rc = wait_event_interruptible_lock_irq(__zfcp_diag_publish_wait,
hdr->updating == 0,
hdr->access_lock);
rc = (rc == 0 ? -EAGAIN : -EINTR);
} else {
hdr->updating = 1;
spin_unlock_irqrestore(&hdr->access_lock, *flags);
/* unlocked, because update function sleeps */
rc = buffer_update(adapter);
spin_lock_irqsave(&hdr->access_lock, *flags);
hdr->updating = 0;
/*
* every thread waiting here went via an interruptible wait,
* so its fine to only wake those
*/
wake_up_interruptible_all(&__zfcp_diag_publish_wait);
}
return rc;
}
static bool
__zfcp_diag_test_buffer_age_isfresh(const struct zfcp_diag_adapter *const diag,
const struct zfcp_diag_header *const hdr)
__must_hold(hdr->access_lock)
{
const unsigned long now = jiffies;
/*
* Should not happen (data is from the future).. if it does, still
* signal that it needs refresh
*/
if (!time_after_eq(now, hdr->timestamp))
return false;
if (jiffies_to_msecs(now - hdr->timestamp) >= diag->max_age)
return false;
return true;
}
/**
* zfcp_diag_update_buffer_limited() - Collect diagnostics and update a
* diagnostics buffer rate limited.
* @adapter: Adapter to collect the diagnostics from.
* @hdr: buffer-header for which to update with the collected diagnostics.
* @buffer_update: Specific implementation for collecting and updating.
*
* This function will cause an update of the given @hdr by calling the also
* given @buffer_update function. If called by multiple sources at the same
* time, it will synchornize the update by only allowing one source to call
* @buffer_update and the others to wait for that source to complete instead
* (the wait is interruptible).
*
* Additionally this version is rate-limited and will only exit if either the
* buffer is fresh enough (within the limit) - it will do nothing if the buffer
* is fresh enough to begin with -, or if the source/thread that started this
* update is the one that made the update (to prevent endless loops).
*
* Return:
* * 0 - If the update was successfully published and/or the buffer is
* fresh enough
* * -EINTR - If the thread went into the wait-state and was interrupted
* * whatever @buffer_update returns
*/
int zfcp_diag_update_buffer_limited(struct zfcp_adapter *const adapter,
struct zfcp_diag_header *const hdr,
zfcp_diag_update_buffer_func buffer_update)
{
unsigned long flags;
int rc;
spin_lock_irqsave(&hdr->access_lock, flags);
for (rc = 0;
!__zfcp_diag_test_buffer_age_isfresh(adapter->diagnostics, hdr);
rc = 0) {
rc = __zfcp_diag_update_buffer(adapter, hdr, buffer_update,
&flags);
if (rc != -EAGAIN)
break;
}
spin_unlock_irqrestore(&hdr->access_lock, flags);
return rc;
}
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