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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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b4563e891a
To fetch a pending channel report word (crw) we use a kernel thread which triggers stcrw and sleeps on a semaphore. The s390 machine check handler uses crw_handle_channel_report to handle one crw if needed. This patch replaces the semaphore with a waitqueue (to block the kernel thread) and an atomic_t (to count the number of pending requests). By this we achieve the ability to force this thread to check for a pending crw (independent on when it is triggered by the machine check handler) and wait for this action to finish. Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
161 lines
4.0 KiB
C
161 lines
4.0 KiB
C
/*
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* Channel report handling code
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*
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* Copyright IBM Corp. 2000,2009
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* Author(s): Ingo Adlung <adlung@de.ibm.com>,
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* Martin Schwidefsky <schwidefsky@de.ibm.com>,
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* Cornelia Huck <cornelia.huck@de.ibm.com>,
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* Heiko Carstens <heiko.carstens@de.ibm.com>,
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*/
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#include <linux/mutex.h>
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#include <linux/kthread.h>
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#include <linux/init.h>
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#include <linux/wait.h>
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#include <asm/crw.h>
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static DEFINE_MUTEX(crw_handler_mutex);
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static crw_handler_t crw_handlers[NR_RSCS];
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static atomic_t crw_nr_req = ATOMIC_INIT(0);
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static DECLARE_WAIT_QUEUE_HEAD(crw_handler_wait_q);
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/**
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* crw_register_handler() - register a channel report word handler
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* @rsc: reporting source code to handle
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* @handler: handler to be registered
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*
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* Returns %0 on success and a negative error value otherwise.
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*/
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int crw_register_handler(int rsc, crw_handler_t handler)
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{
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int rc = 0;
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if ((rsc < 0) || (rsc >= NR_RSCS))
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return -EINVAL;
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mutex_lock(&crw_handler_mutex);
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if (crw_handlers[rsc])
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rc = -EBUSY;
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else
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crw_handlers[rsc] = handler;
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mutex_unlock(&crw_handler_mutex);
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return rc;
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}
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/**
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* crw_unregister_handler() - unregister a channel report word handler
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* @rsc: reporting source code to handle
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*/
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void crw_unregister_handler(int rsc)
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{
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if ((rsc < 0) || (rsc >= NR_RSCS))
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return;
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mutex_lock(&crw_handler_mutex);
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crw_handlers[rsc] = NULL;
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mutex_unlock(&crw_handler_mutex);
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}
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/*
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* Retrieve CRWs and call function to handle event.
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*/
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static int crw_collect_info(void *unused)
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{
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struct crw crw[2];
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int ccode, signal;
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unsigned int chain;
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repeat:
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signal = wait_event_interruptible(crw_handler_wait_q,
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atomic_read(&crw_nr_req) > 0);
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if (unlikely(signal))
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atomic_inc(&crw_nr_req);
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chain = 0;
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while (1) {
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crw_handler_t handler;
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if (unlikely(chain > 1)) {
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struct crw tmp_crw;
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printk(KERN_WARNING"%s: Code does not support more "
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"than two chained crws; please report to "
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"linux390@de.ibm.com!\n", __func__);
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ccode = stcrw(&tmp_crw);
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printk(KERN_WARNING"%s: crw reports slct=%d, oflw=%d, "
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"chn=%d, rsc=%X, anc=%d, erc=%X, rsid=%X\n",
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__func__, tmp_crw.slct, tmp_crw.oflw,
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tmp_crw.chn, tmp_crw.rsc, tmp_crw.anc,
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tmp_crw.erc, tmp_crw.rsid);
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printk(KERN_WARNING"%s: This was crw number %x in the "
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"chain\n", __func__, chain);
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if (ccode != 0)
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break;
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chain = tmp_crw.chn ? chain + 1 : 0;
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continue;
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}
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ccode = stcrw(&crw[chain]);
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if (ccode != 0)
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break;
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printk(KERN_DEBUG "crw_info : CRW reports slct=%d, oflw=%d, "
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"chn=%d, rsc=%X, anc=%d, erc=%X, rsid=%X\n",
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crw[chain].slct, crw[chain].oflw, crw[chain].chn,
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crw[chain].rsc, crw[chain].anc, crw[chain].erc,
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crw[chain].rsid);
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/* Check for overflows. */
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if (crw[chain].oflw) {
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int i;
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pr_debug("%s: crw overflow detected!\n", __func__);
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mutex_lock(&crw_handler_mutex);
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for (i = 0; i < NR_RSCS; i++) {
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if (crw_handlers[i])
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crw_handlers[i](NULL, NULL, 1);
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}
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mutex_unlock(&crw_handler_mutex);
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chain = 0;
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continue;
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}
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if (crw[0].chn && !chain) {
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chain++;
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continue;
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}
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mutex_lock(&crw_handler_mutex);
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handler = crw_handlers[crw[chain].rsc];
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if (handler)
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handler(&crw[0], chain ? &crw[1] : NULL, 0);
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mutex_unlock(&crw_handler_mutex);
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/* chain is always 0 or 1 here. */
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chain = crw[chain].chn ? chain + 1 : 0;
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}
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if (atomic_dec_and_test(&crw_nr_req))
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wake_up(&crw_handler_wait_q);
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goto repeat;
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return 0;
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}
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void crw_handle_channel_report(void)
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{
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atomic_inc(&crw_nr_req);
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wake_up(&crw_handler_wait_q);
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}
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void crw_wait_for_channel_report(void)
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{
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crw_handle_channel_report();
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wait_event(crw_handler_wait_q, atomic_read(&crw_nr_req) == 0);
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}
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/*
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* Machine checks for the channel subsystem must be enabled
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* after the channel subsystem is initialized
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*/
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static int __init crw_machine_check_init(void)
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{
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struct task_struct *task;
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task = kthread_run(crw_collect_info, NULL, "kmcheck");
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if (IS_ERR(task))
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return PTR_ERR(task);
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ctl_set_bit(14, 28); /* enable channel report MCH */
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return 0;
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}
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device_initcall(crw_machine_check_init);
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