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#include <linux/types.h>
#include <linux/errno.h>
#include <linux/platform_device.h>
#include <linux/pid.h>
#include <linux/version.h>
#if LINUX_VERSION_CODE >= KERNEL_VERSION(4,11,0)
#include <linux/signalfd.h>
#endif
#include "mts_io_module.h"
#include "radio_udev_discovery.h"
/*
* radio-reset in the mts-io driver sets radio_udev_discovery to 0.
* Then it returns early if radio_udev_discovery is set to 1. The
* UDEV daemon is used to set radio_udev_discovery. Notifications
* are sent if radio_udev_discovery goes from 0 to 1.
*/
int radio_udev_discovery = 1;
struct sig_pid_radio_reset_monitor_s {
pid_t pid;
int signal;
struct pid *vpid;
};
#define PID_MAX_COUNT 20
static struct sig_pid_radio_reset_monitor_s sig_pid_radio_reset_monitor[PID_MAX_COUNT];
/* Clear an entry in the table that no longer exists.
* unlocks the mts_io_lock, toggles the rcu_read_lock,
* then puts back the mts_io_lock.
*/
static int
verify_vpid(struct sig_pid_radio_reset_monitor_s *p)
{
pid_t pid0 = p->pid;
struct pid *vpid1;
struct pid *vpid0 = p->vpid;
unsigned int vcount;
// Check to see if vpid and pid still match
if (p->pid == 0)
return 0;
if (vpid0 == NULL) {
p->pid = 0;
return 0;
}
mutex_unlock(&mts_io_mutex);
rcu_read_lock();
vpid1 = find_vpid((pid_t)pid0);
if(vpid1 != NULL) {
#if LINUX_VERSION_CODE >= KERNEL_VERSION(4,15,0)
vcount = refcount_read(&vpid1->count);
#else
vcount = atomic_read(&vpid1->count);
#endif
} else
vcount = 0;
rcu_read_unlock();
mutex_lock(&mts_io_mutex);
if ((vpid1 != vpid0) || (vpid1 == NULL))
p->pid = 0;
pr_debug("%s: verify_vpid: vpid0 0x%x vpid1 0x%x vcount %d for pid %d\n",
__FUNCTION__,
(unsigned int)vpid0, (unsigned int)vpid1, vcount, (int)pid0);
return p->pid;
}
// Need to find existing entries and allow updates. Signal 0 removes a value.
ssize_t mts_attr_store_radio_reset_monitor(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
{
long pid0;
int sig;
int i;
int found;
struct pid *vpid1, *vpid0;
int retval;
retval = sscanf(buf, "%ld %d", &pid0, &sig);
if (retval != 2)
return -EINVAL;
if (pid0 < 0)
return -EINVAL;
rcu_read_lock();
vpid0 = find_vpid((pid_t)pid0);
rcu_read_unlock();
pr_debug("%s: Try to store %ld %d 0x%x\n",
__FUNCTION__,
pid0,sig,(unsigned int)vpid0);
if (vpid0) {
/* Note that since we no longer hold the rcu lock, vpid
* could become invalid, unless it is ours.
*/
mutex_lock(&mts_io_mutex);
/* First see if we are already in the table -- search whole table */
found = -1;
for (i=0; i < PID_MAX_COUNT; i++) {
if ((sig_pid_radio_reset_monitor[i].pid == (pid_t)pid0) &&
(sig_pid_radio_reset_monitor[i].vpid == vpid0)) {
if (sig == 0) {
sig_pid_radio_reset_monitor[i].pid = 0;
sig_pid_radio_reset_monitor[i].vpid = NULL;
} else {
sig_pid_radio_reset_monitor[i].signal = sig;
mutex_unlock(&mts_io_mutex);
rcu_read_lock();
vpid0 = find_vpid((pid_t)pid0);
rcu_read_unlock();
pr_debug("%s: slot %d: pid %d, vpid 0x%x/vpid 0x%x\n",
__FUNCTION__,
i,(int)pid0,(unsigned int)vpid0,
(unsigned int)sig_pid_radio_reset_monitor[i].vpid);
mutex_lock(&mts_io_mutex);
if (vpid0 != sig_pid_radio_reset_monitor[i].vpid) {
sig_pid_radio_reset_monitor[i].pid = 0; /* Maybe exited? */
sig_pid_radio_reset_monitor[i].vpid = NULL;
pr_debug("%s: mts-io: vpid mismatch pid %d, vpid 0x%x/0x%x, sig %d, cleared %d\n",
__FUNCTION__,
(int)sig_pid_radio_reset_monitor[i].pid,
(unsigned int)sig_pid_radio_reset_monitor[i].vpid,(unsigned int)vpid0,
(unsigned int)sig_pid_radio_reset_monitor[i].signal,i);
} else {
found = i;
pr_debug("%s: mts-io: found pid %d, vpid 0x%x, sig %d\n",
__FUNCTION__,
(int)sig_pid_radio_reset_monitor[i].pid,
(unsigned int)sig_pid_radio_reset_monitor[i].vpid,
(unsigned int)sig_pid_radio_reset_monitor[i].signal);
sig = 0; // Clear any more that we find.
}
}
} // Location matches our pid
} // Loop through table
pr_debug("%s: found=%d, sig=%d\n",__FUNCTION__,found,sig);
if (found > -1) {
mutex_unlock(&mts_io_mutex);
return count;
}
if (sig == 0) {
// Nothing to clear out.
mutex_unlock(&mts_io_mutex);
return count;
}
/* Need to find an unused slot and save our signal and PID.
* Still holding mutex_lock(&mts_io_mutex)
* Find first open slot
*/
found = -1;
for (i=0; i < PID_MAX_COUNT; i++) {
if (sig_pid_radio_reset_monitor[i].pid == 0) {
sig_pid_radio_reset_monitor[i].pid = (pid_t)pid0;
sig_pid_radio_reset_monitor[i].signal = sig;
sig_pid_radio_reset_monitor[i].vpid = vpid0;
pr_debug("%s: mts-io: open slot: pid %d, vpid 0x%x, sig %d, slot %d\n",
__FUNCTION__,
(int)pid0,
(unsigned int)vpid0,
(unsigned int)sig, i);
found = i;
break;
} else {
// See if this slot may be used.
pid_t pid1 = sig_pid_radio_reset_monitor[i].pid;
if (pid1 > 0) {
mutex_unlock(&mts_io_mutex);
rcu_read_lock();
vpid1 = find_vpid((pid_t)pid1);
rcu_read_unlock();
mutex_lock(&mts_io_mutex);
// See if pid and vpid still exists
if (!vpid1 || (vpid1 != sig_pid_radio_reset_monitor[i].vpid)) {
// Make sure no one else has claimed this slot
if (pid1 == sig_pid_radio_reset_monitor[i].pid) {
sig_pid_radio_reset_monitor[i].pid = 0;
sig_pid_radio_reset_monitor[i].vpid = NULL;
i--; // Should be able to use this slot.
continue;
} // Has not been re-claimed.
} // Slot has no user or exited user
} // Verify that slot in use is still in use
} // Found an empty slot
} // Loop through all the slots.
mutex_unlock(&mts_io_mutex);
} // pid is in pid table
return count;
}
// Examples say buf is PAGE_SIZE long
ssize_t mts_attr_show_radio_reset_monitor(struct device *dev,
struct device_attribute *attr,
char *buf)
{
int count;
int max = PAGE_SIZE;
int ret;
int i;
pid_t pid1;
mutex_lock(&mts_io_mutex);
count = 0;
for (i=0; i < PID_MAX_COUNT; i++) {
pid1 = verify_vpid(sig_pid_radio_reset_monitor + i);
if (pid1 == 0) {
sig_pid_radio_reset_monitor[i].pid = 0;
sig_pid_radio_reset_monitor[i].vpid = NULL;
continue;
}
pr_debug("%s: found a pid in slot %d\n",__FUNCTION__,i);
ret = snprintf(buf+count, max, "%lu %d\n",
(unsigned long)pid1,
sig_pid_radio_reset_monitor[i].signal);
if (ret > 0) {
max -= ret;
count += ret;
}
if (max == 0)
break;
if(ret == 0)
break;
} // Loop through all the slots until we are full.
mutex_unlock(&mts_io_mutex);
return count;
}
/*
* After a radio reset, prime the flag, so if it is set to one
* after this, then we wake the processes waiting on the flag.
* Caller holds the mts_io_mutex lock.
*/
void
reset_radio_udev_discovery(void)
{
radio_udev_discovery = 0;
}
int
udev_discovered_radio(void)
{
return radio_udev_discovery;
}
ssize_t mts_attr_show_radio_udev_discovery(struct device *dev,
struct device_attribute *attr,
char *buf)
{
return sprintf(buf, "%d\n", radio_udev_discovery);
}
ssize_t mts_attr_store_radio_udev_discovery(struct device *dev,
struct device_attribute *attr, const char *buf, size_t count)
{
int value = -1;
pid_t pid1;
struct pid *vpid0, *vpid1;
int sig, i;
int retval;
retval = sscanf(buf, "%i", &value);
if (retval != 1)
return -EINVAL;
if (radio_udev_discovery == -1) {
// Not ready
return -EPROTO;
}
// Only driver can set this to zero.
if (value == 0)
return -EINVAL;
mutex_lock(&mts_io_mutex);
if((value == 1) && (radio_udev_discovery == 0)) {
radio_udev_discovery = 1;
pr_debug("%s: mts-io: UDEV discovered cellular modem after radio-reset so signal registered processes",
__FUNCTION__);
// kill all processes that are queued
for (i=0; i < PID_MAX_COUNT; i++) {
pid1 = verify_vpid(sig_pid_radio_reset_monitor + i);
if (pid1 == 0) continue;
sig = sig_pid_radio_reset_monitor[i].signal;
vpid0 = sig_pid_radio_reset_monitor[i].vpid;
mutex_unlock(&mts_io_mutex);
rcu_read_lock();
vpid1 = find_vpid(pid1);
if (vpid1 == vpid0) {
printk(KERN_ALERT
"mts-io: %s: Sending signal %d to pid %d due to UDEV radio discovery\n",
__FUNCTION__,
sig,pid1);
kill_pid(vpid1,sig,1);
} // vpid is valid, same as registered
else {
printk(KERN_ALERT
"mts-io: %s: mismatched vpid %x/%x\n", __FUNCTION__, (unsigned int)vpid1, (unsigned int) vpid0);
}
rcu_read_unlock();
mutex_lock(&mts_io_mutex);
} // Find empty slot
} // udev wants us to wake everybody up after reset
mutex_unlock(&mts_io_mutex);
return count;
}
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