OMAPDSS: VENC: fix NULL pointer dereference in DSS2 VENC sysfs debug attr on OMAP4

[zen-stable.git] / drivers / edac / edac_pci.c

/*
 * EDAC PCI component
 *
 * Author: Dave Jiang <djiang@mvista.com>
 *
 * 2007 (c) MontaVista Software, Inc. This file is licensed under
 * the terms of the GNU General Public License version 2. This program
 * is licensed "as is" without any warranty of any kind, whether express
 * or implied.
 *
 */
#include <linux/module.h>
#include <linux/types.h>
#include <linux/smp.h>
#include <linux/init.h>
#include <linux/sysctl.h>
#include <linux/highmem.h>
#include <linux/timer.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/list.h>
#include <linux/ctype.h>
#include <linux/workqueue.h>
#include <asm/uaccess.h>
#include <asm/page.h>

#include "edac_core.h"
#include "edac_module.h"

static DEFINE_MUTEX(edac_pci_ctls_mutex);
static LIST_HEAD(edac_pci_list);
static atomic_t pci_indexes = ATOMIC_INIT(0);

/*
 * edac_pci_alloc_ctl_info
 *
 *      The alloc() function for the 'edac_pci' control info
 *      structure. The chip driver will allocate one of these for each
 *      edac_pci it is going to control/register with the EDAC CORE.
 */
struct edac_pci_ctl_info *edac_pci_alloc_ctl_info(unsigned int sz_pvt,
                                                const char *edac_pci_name)
{
        struct edac_pci_ctl_info *pci;
        void *pvt;
        unsigned int size;

        debugf1("%s()\n", __func__);

        pci = (struct edac_pci_ctl_info *)0;
        pvt = edac_align_ptr(&pci[1], sz_pvt);
        size = ((unsigned long)pvt) + sz_pvt;

        /* Alloc the needed control struct memory */
        pci = kzalloc(size, GFP_KERNEL);
        if (pci  == NULL)
                return NULL;

        /* Now much private space */
        pvt = sz_pvt ? ((char *)pci) + ((unsigned long)pvt) : NULL;

        pci->pvt_info = pvt;
        pci->op_state = OP_ALLOC;

        snprintf(pci->name, strlen(edac_pci_name) + 1, "%s", edac_pci_name);

        return pci;
}
EXPORT_SYMBOL_GPL(edac_pci_alloc_ctl_info);

/*
 * edac_pci_free_ctl_info()
 *
 *      Last action on the pci control structure.
 *
 *      call the remove sysfs information, which will unregister
 *      this control struct's kobj. When that kobj's ref count
 *      goes to zero, its release function will be call and then
 *      kfree() the memory.
 */
void edac_pci_free_ctl_info(struct edac_pci_ctl_info *pci)
{
        debugf1("%s()\n", __func__);

        edac_pci_remove_sysfs(pci);
}
EXPORT_SYMBOL_GPL(edac_pci_free_ctl_info);

/*
 * find_edac_pci_by_dev()
 *      scans the edac_pci list for a specific 'struct device *'
 *
 *      return NULL if not found, or return control struct pointer
 */
static struct edac_pci_ctl_info *find_edac_pci_by_dev(struct device *dev)
{
        struct edac_pci_ctl_info *pci;
        struct list_head *item;

        debugf1("%s()\n", __func__);

        list_for_each(item, &edac_pci_list) {
                pci = list_entry(item, struct edac_pci_ctl_info, link);

                if (pci->dev == dev)
                        return pci;
        }

        return NULL;
}

/*
 * add_edac_pci_to_global_list
 *      Before calling this function, caller must assign a unique value to
 *      edac_dev->pci_idx.
 *      Return:
 *              0 on success
 *              1 on failure
 */
static int add_edac_pci_to_global_list(struct edac_pci_ctl_info *pci)
{
        struct list_head *item, *insert_before;
        struct edac_pci_ctl_info *rover;

        debugf1("%s()\n", __func__);

        insert_before = &edac_pci_list;

        /* Determine if already on the list */
        rover = find_edac_pci_by_dev(pci->dev);
        if (unlikely(rover != NULL))
                goto fail0;

        /* Insert in ascending order by 'pci_idx', so find position */
        list_for_each(item, &edac_pci_list) {
                rover = list_entry(item, struct edac_pci_ctl_info, link);

                if (rover->pci_idx >= pci->pci_idx) {
                        if (unlikely(rover->pci_idx == pci->pci_idx))
                                goto fail1;

                        insert_before = item;
                        break;
                }
        }

        list_add_tail_rcu(&pci->link, insert_before);
        return 0;

fail0:
        edac_printk(KERN_WARNING, EDAC_PCI,
                "%s (%s) %s %s already assigned %d\n",
                dev_name(rover->dev), edac_dev_name(rover),
                rover->mod_name, rover->ctl_name, rover->pci_idx);
        return 1;

fail1:
        edac_printk(KERN_WARNING, EDAC_PCI,
                "but in low-level driver: attempt to assign\n"
                "\tduplicate pci_idx %d in %s()\n", rover->pci_idx,
                __func__);
        return 1;
}

/*
 * del_edac_pci_from_global_list
 *
 *      remove the PCI control struct from the global list
 */
static void del_edac_pci_from_global_list(struct edac_pci_ctl_info *pci)
{
        list_del_rcu(&pci->link);

        /* these are for safe removal of devices from global list while
         * NMI handlers may be traversing list
         */
        synchronize_rcu();
        INIT_LIST_HEAD(&pci->link);
}

#if 0
/* Older code, but might use in the future */

/*
 * edac_pci_find()
 *      Search for an edac_pci_ctl_info structure whose index is 'idx'
 *
 * If found, return a pointer to the structure
 * Else return NULL.
 *
 * Caller must hold pci_ctls_mutex.
 */
struct edac_pci_ctl_info *edac_pci_find(int idx)
{
        struct list_head *item;
        struct edac_pci_ctl_info *pci;

        /* Iterage over list, looking for exact match of ID */
        list_for_each(item, &edac_pci_list) {
                pci = list_entry(item, struct edac_pci_ctl_info, link);

                if (pci->pci_idx >= idx) {
                        if (pci->pci_idx == idx)
                                return pci;

                        /* not on list, so terminate early */
                        break;
                }
        }

        return NULL;
}
EXPORT_SYMBOL_GPL(edac_pci_find);
#endif

/*
 * edac_pci_workq_function()
 *
 *      periodic function that performs the operation
 *      scheduled by a workq request, for a given PCI control struct
 */
static void edac_pci_workq_function(struct work_struct *work_req)
{
        struct delayed_work *d_work = to_delayed_work(work_req);
        struct edac_pci_ctl_info *pci = to_edac_pci_ctl_work(d_work);
        int msec;
        unsigned long delay;

        debugf3("%s() checking\n", __func__);

        mutex_lock(&edac_pci_ctls_mutex);

        if (pci->op_state == OP_RUNNING_POLL) {
                /* we might be in POLL mode, but there may NOT be a poll func
                 */
                if ((pci->edac_check != NULL) && edac_pci_get_check_errors())
                        pci->edac_check(pci);

                /* if we are on a one second period, then use round */
                msec = edac_pci_get_poll_msec();
                if (msec == 1000)
                        delay = round_jiffies_relative(msecs_to_jiffies(msec));
                else
                        delay = msecs_to_jiffies(msec);

                /* Reschedule only if we are in POLL mode */
                queue_delayed_work(edac_workqueue, &pci->work, delay);
        }

        mutex_unlock(&edac_pci_ctls_mutex);
}

/*
 * edac_pci_workq_setup()
 *      initialize a workq item for this edac_pci instance
 *      passing in the new delay period in msec
 *
 *      locking model:
 *              called when 'edac_pci_ctls_mutex' is locked
 */
static void edac_pci_workq_setup(struct edac_pci_ctl_info *pci,
                                 unsigned int msec)
{
        debugf0("%s()\n", __func__);

        INIT_DELAYED_WORK(&pci->work, edac_pci_workq_function);
        queue_delayed_work(edac_workqueue, &pci->work,
                        msecs_to_jiffies(edac_pci_get_poll_msec()));
}

/*
 * edac_pci_workq_teardown()
 *      stop the workq processing on this edac_pci instance
 */
static void edac_pci_workq_teardown(struct edac_pci_ctl_info *pci)
{
        int status;

        debugf0("%s()\n", __func__);

        status = cancel_delayed_work(&pci->work);
        if (status == 0)
                flush_workqueue(edac_workqueue);
}

/*
 * edac_pci_reset_delay_period
 *
 *      called with a new period value for the workq period
 *      a) stop current workq timer
 *      b) restart workq timer with new value
 */
void edac_pci_reset_delay_period(struct edac_pci_ctl_info *pci,
                                 unsigned long value)
{
        debugf0("%s()\n", __func__);

        edac_pci_workq_teardown(pci);

        /* need to lock for the setup */
        mutex_lock(&edac_pci_ctls_mutex);

        edac_pci_workq_setup(pci, value);

        mutex_unlock(&edac_pci_ctls_mutex);
}
EXPORT_SYMBOL_GPL(edac_pci_reset_delay_period);

/*
 * edac_pci_alloc_index: Allocate a unique PCI index number
 *
 * Return:
 *      allocated index number
 *
 */
int edac_pci_alloc_index(void)
{
        return atomic_inc_return(&pci_indexes) - 1;
}
EXPORT_SYMBOL_GPL(edac_pci_alloc_index);

/*
 * edac_pci_add_device: Insert the 'edac_dev' structure into the
 * edac_pci global list and create sysfs entries associated with
 * edac_pci structure.
 * @pci: pointer to the edac_device structure to be added to the list
 * @edac_idx: A unique numeric identifier to be assigned to the
 * 'edac_pci' structure.
 *
 * Return:
 *      0       Success
 *      !0      Failure
 */
int edac_pci_add_device(struct edac_pci_ctl_info *pci, int edac_idx)
{
        debugf0("%s()\n", __func__);

        pci->pci_idx = edac_idx;
        pci->start_time = jiffies;

        mutex_lock(&edac_pci_ctls_mutex);

        if (add_edac_pci_to_global_list(pci))
                goto fail0;

        if (edac_pci_create_sysfs(pci)) {
                edac_pci_printk(pci, KERN_WARNING,
                                "failed to create sysfs pci\n");
                goto fail1;
        }

        if (pci->edac_check != NULL) {
                pci->op_state = OP_RUNNING_POLL;

                edac_pci_workq_setup(pci, 1000);
        } else {
                pci->op_state = OP_RUNNING_INTERRUPT;
        }

        edac_pci_printk(pci, KERN_INFO,
                        "Giving out device to module '%s' controller '%s':"
                        " DEV '%s' (%s)\n",
                        pci->mod_name,
                        pci->ctl_name,
                        edac_dev_name(pci), edac_op_state_to_string(pci->op_state));

        mutex_unlock(&edac_pci_ctls_mutex);
        return 0;

        /* error unwind stack */
fail1:
        del_edac_pci_from_global_list(pci);
fail0:
        mutex_unlock(&edac_pci_ctls_mutex);
        return 1;
}
EXPORT_SYMBOL_GPL(edac_pci_add_device);

/*
 * edac_pci_del_device()
 *      Remove sysfs entries for specified edac_pci structure and
 *      then remove edac_pci structure from global list
 *
 * @dev:
 *      Pointer to 'struct device' representing edac_pci structure
 *      to remove
 *
 * Return:
 *      Pointer to removed edac_pci structure,
 *      or NULL if device not found
 */
struct edac_pci_ctl_info *edac_pci_del_device(struct device *dev)
{
        struct edac_pci_ctl_info *pci;

        debugf0("%s()\n", __func__);

        mutex_lock(&edac_pci_ctls_mutex);

        /* ensure the control struct is on the global list
         * if not, then leave
         */
        pci = find_edac_pci_by_dev(dev);
        if (pci  == NULL) {
                mutex_unlock(&edac_pci_ctls_mutex);
                return NULL;
        }

        pci->op_state = OP_OFFLINE;

        del_edac_pci_from_global_list(pci);

        mutex_unlock(&edac_pci_ctls_mutex);

        /* stop the workq timer */
        edac_pci_workq_teardown(pci);

        edac_printk(KERN_INFO, EDAC_PCI,
                "Removed device %d for %s %s: DEV %s\n",
                pci->pci_idx, pci->mod_name, pci->ctl_name, edac_dev_name(pci));

        return pci;
}
EXPORT_SYMBOL_GPL(edac_pci_del_device);

/*
 * edac_pci_generic_check
 *
 *      a Generic parity check API
 */
static void edac_pci_generic_check(struct edac_pci_ctl_info *pci)
{
        debugf4("%s()\n", __func__);
        edac_pci_do_parity_check();
}

/* free running instance index counter */
static int edac_pci_idx;
#define EDAC_PCI_GENCTL_NAME    "EDAC PCI controller"

struct edac_pci_gen_data {
        int edac_idx;
};

/*
 * edac_pci_create_generic_ctl
 *
 *      A generic constructor for a PCI parity polling device
 *      Some systems have more than one domain of PCI busses.
 *      For systems with one domain, then this API will
 *      provide for a generic poller.
 *
 *      This routine calls the edac_pci_alloc_ctl_info() for
 *      the generic device, with default values
 */
struct edac_pci_ctl_info *edac_pci_create_generic_ctl(struct device *dev,
                                                const char *mod_name)
{
        struct edac_pci_ctl_info *pci;
        struct edac_pci_gen_data *pdata;

        pci = edac_pci_alloc_ctl_info(sizeof(*pdata), EDAC_PCI_GENCTL_NAME);
        if (!pci)
                return NULL;

        pdata = pci->pvt_info;
        pci->dev = dev;
        dev_set_drvdata(pci->dev, pci);
        pci->dev_name = pci_name(to_pci_dev(dev));

        pci->mod_name = mod_name;
        pci->ctl_name = EDAC_PCI_GENCTL_NAME;
        pci->edac_check = edac_pci_generic_check;

        pdata->edac_idx = edac_pci_idx++;

        if (edac_pci_add_device(pci, pdata->edac_idx) > 0) {
                debugf3("%s(): failed edac_pci_add_device()\n", __func__);
                edac_pci_free_ctl_info(pci);
                return NULL;
        }

        return pci;
}
EXPORT_SYMBOL_GPL(edac_pci_create_generic_ctl);

/*
 * edac_pci_release_generic_ctl
 *
 *      The release function of a generic EDAC PCI polling device
 */
void edac_pci_release_generic_ctl(struct edac_pci_ctl_info *pci)
{
        debugf0("%s() pci mod=%s\n", __func__, pci->mod_name);

        edac_pci_del_device(pci->dev);
        edac_pci_free_ctl_info(pci);
}
EXPORT_SYMBOL_GPL(edac_pci_release_generic_ctl);