minix/drivers/log/log.c
Cristiano Giuffrida 1f5841c8ed Basic System Event Framework (SEF) with ping and live update.
SYSLIB CHANGES:
- SEF must be used by every system process and is thereby part of the system
library.
- The framework provides a receive() interface (sef_receive) for system
processes to automatically catch known system even messages and process them.
- SEF provides a default behavior for each type of system event, but allows
system processes to register callbacks to override the default behavior.
- Custom (local to the process) or predefined (provided by SEF) callback
implementations can be registered to SEF.
- SEF currently includes support for 2 types of system events:
  1. SEF Ping. The event occurs every time RS sends a ping to figure out
  whether a system process is still alive. The default callback implementation
  provided by SEF is to notify RS back to let it know the process is alive
  and kicking.
  2. SEF Live update. The event occurs every time RS sends a prepare to update
  message to let a system process know an update is available and to prepare
  for it. The live update support is very basic for now. SEF only deals with
  verifying if the prepare state can be supported by the process, dumping the
  state for debugging purposes, and providing an event-driven programming
  model to the process to react to state changes check-in when ready to update.
- SEF should be extended in the future to integrate support for more types of
system events. Ideally, all the cross-cutting concerns should be integrated into
SEF to avoid duplicating code and ease extensibility. Examples include:
  * PM notify messages primarily used at shutdown.
  * SYSTEM notify messages primarily used for signals.
  * CLOCK notify messages used for system alarms.
  * Debug messages. IS could still be in charge of fkey handling but would
  forward the debug message to the target process (e.g. PM, if the user
  requested debug information about PM). SEF would then catch the message and
  do nothing unless the process has registered an appropriate callback to
  deal with the event. This simplifies the programming model to print debug
  information, avoids duplicating code, and reduces the effort to print
  debug information.

SYSTEM PROCESSES CHANGES:
- Every system process registers SEF callbacks it needs to override the default
system behavior and calls sef_startup() right after being started.
- sef_startup() does almost nothing now, but will be extended in the future to
support callbacks of its own to let RS control and synchronize with every
system process at initialization time.
- Every system process calls sef_receive() now rather than receive() directly,
to let SEF handle predefined system events.

RS CHANGES:
- RS supports a basic single-component live update protocol now, as follows:
  * When an update command is issued (via "service update *"), RS notifies the
  target system process to prepare for a specific update state.
  * If the process doesn't respond back in time, the update is aborted.
  * When the process responds back, RS kills it and marks it for refreshing.
  * The process is then automatically restarted as for a buggy process and can
  start running again.
  * Live update is currently prototyped as a controlled failure.
2009-12-21 14:12:21 +00:00

490 lines
14 KiB
C

/* This file contains a driver for:
* /dev/klog - system log device
*
* Changes:
* 21 July 2005 - Support for diagnostic messages (Jorrit N. Herder)
* 7 July 2005 - Created (Ben Gras)
*/
#include "log.h"
#include <sys/time.h>
#include <sys/select.h>
#include <minix/endpoint.h>
#define LOG_DEBUG 0 /* enable/ disable debugging */
#define NR_DEVS 1 /* number of minor devices */
#define MINOR_KLOG 0 /* /dev/klog */
#define LOGINC(n, i) do { (n) = (((n) + (i)) % LOG_SIZE); } while(0)
PUBLIC struct logdevice logdevices[NR_DEVS];
PRIVATE struct device log_geom[NR_DEVS]; /* base and size of devices */
PRIVATE int log_device = -1; /* current device */
FORWARD _PROTOTYPE( char *log_name, (void) );
FORWARD _PROTOTYPE( struct device *log_prepare, (int device) );
FORWARD _PROTOTYPE( int log_transfer, (int proc_nr, int opcode, u64_t position,
iovec_t *iov, unsigned nr_req) );
FORWARD _PROTOTYPE( int log_do_open, (struct driver *dp, message *m_ptr) );
FORWARD _PROTOTYPE( int log_cancel, (struct driver *dp, message *m_ptr) );
FORWARD _PROTOTYPE( int log_select, (struct driver *dp, message *m_ptr) );
FORWARD _PROTOTYPE( void log_signal, (struct driver *dp, sigset_t *set) );
FORWARD _PROTOTYPE( int log_other, (struct driver *dp, message *m_ptr) );
FORWARD _PROTOTYPE( void log_geometry, (struct partition *entry) );
FORWARD _PROTOTYPE( int subread, (struct logdevice *log, int count, int proc_nr, vir_bytes user_vir, size_t) );
/* Entry points to this driver. */
PRIVATE struct driver log_dtab = {
log_name, /* current device's name */
log_do_open, /* open or mount */
do_nop, /* nothing on a close */
nop_ioctl, /* ioctl nop */
log_prepare, /* prepare for I/O on a given minor device */
log_transfer, /* do the I/O */
nop_cleanup, /* no need to clean up */
log_geometry, /* geometry */
log_signal, /* handle system signal */
nop_alarm, /* no alarm */
log_cancel, /* CANCEL request */
log_select, /* DEV_SELECT request */
log_other, /* Unrecognized messages */
NULL /* HW int */
};
extern int device_caller;
/* SEF functions and variables. */
FORWARD _PROTOTYPE( void sef_local_startup, (void) );
EXTERN _PROTOTYPE( void sef_cb_lu_prepare, (int state) );
EXTERN _PROTOTYPE( int sef_cb_lu_state_isvalid, (int state) );
EXTERN _PROTOTYPE( void sef_cb_lu_state_dump, (int state) );
/*===========================================================================*
* main *
*===========================================================================*/
PUBLIC int main(void)
{
int i;
/* SEF local startup. */
sef_local_startup();
/* Initialize log devices. */
for(i = 0; i < NR_DEVS; i++) {
log_geom[i].dv_size = cvul64(LOG_SIZE);
log_geom[i].dv_base = cvul64((long)logdevices[i].log_buffer);
logdevices[i].log_size = logdevices[i].log_read =
logdevices[i].log_write =
logdevices[i].log_select_alerted =
logdevices[i].log_selected =
logdevices[i].log_select_ready_ops = 0;
logdevices[i].log_proc_nr = 0;
logdevices[i].log_revive_alerted = 0;
}
driver_task(&log_dtab, DRIVER_ASYN);
return(OK);
}
/*===========================================================================*
* sef_local_startup *
*===========================================================================*/
PRIVATE void sef_local_startup()
{
/* Register live update callbacks. */
sef_setcb_lu_prepare(sef_cb_lu_prepare);
sef_setcb_lu_state_isvalid(sef_cb_lu_state_isvalid);
sef_setcb_lu_state_dump(sef_cb_lu_state_dump);
/* Let SEF perform startup. */
sef_startup();
}
/*===========================================================================*
* log_name *
*===========================================================================*/
PRIVATE char *log_name()
{
/* Return a name for the current device. */
static char name[] = "log";
return name;
}
/*===========================================================================*
* log_prepare *
*===========================================================================*/
PRIVATE struct device *log_prepare(device)
int device;
{
/* Prepare for I/O on a device: check if the minor device number is ok. */
if (device < 0 || device >= NR_DEVS) return(NIL_DEV);
log_device = device;
return(&log_geom[device]);
}
/*===========================================================================*
* subwrite *
*===========================================================================*/
PRIVATE int
subwrite(struct logdevice *log, int count, int proc_nr,
vir_bytes user_vir, size_t offset)
{
int d, r;
char *buf;
message m;
if (log->log_write + count > LOG_SIZE)
count = LOG_SIZE - log->log_write;
buf = log->log_buffer + log->log_write;
if(proc_nr == SELF) {
memcpy(buf, (char *) user_vir, count);
}
else {
if((r=sys_safecopyfrom(proc_nr, user_vir, offset,
(vir_bytes)buf, count, D)) != OK)
return r;
}
LOGINC(log->log_write, count);
log->log_size += count;
if(log->log_size > LOG_SIZE) {
int overflow;
overflow = log->log_size - LOG_SIZE;
log->log_size -= overflow;
LOGINC(log->log_read, overflow);
}
if(log->log_size > 0 && log->log_proc_nr && !log->log_revive_alerted) {
/* Someone who was suspended on read can now
* be revived.
*/
log->log_status = subread(log, log->log_iosize,
log->log_proc_nr, log->log_user_vir_g,
log->log_user_vir_offset);
m.m_type = DEV_REVIVE;
m.REP_ENDPT = log->log_proc_nr;
m.REP_STATUS = log->log_status;
m.REP_IO_GRANT = log->log_user_vir_g;
r= send(log->log_source, &m);
if (r != OK)
{
printf("log`subwrite: send to %d failed: %d\n",
log->log_source, r);
}
log->log_proc_nr = 0;
}
if(log->log_size > 0)
log->log_select_ready_ops |= SEL_RD;
if(log->log_size > 0 && log->log_selected &&
!(log->log_select_alerted)) {
/* Someone(s) who was/were select()ing can now
* be awoken. If there was a blocking read (above),
* this can only happen if the blocking read didn't
* swallow all the data (log_size > 0).
*/
if(log->log_selected & SEL_RD) {
d= log-logdevices;
m.m_type = DEV_SEL_REPL2;
m.DEV_SEL_OPS = log->log_select_ready_ops;
m.DEV_MINOR = d;
#if LOG_DEBUG
printf("select sending DEV_SEL_REPL2\n");
#endif
r= send(log->log_select_proc, &m);
if (r != OK)
{
printf(
"log`subwrite: send to %d failed: %d\n",
log->log_select_proc, r);
}
log->log_selected &= ~log->log_select_ready_ops;
}
}
return count;
}
/*===========================================================================*
* log_append *
*===========================================================================*/
PUBLIC void
log_append(char *buf, int count)
{
int w = 0, skip = 0;
if(count < 1) return;
if(count > LOG_SIZE) skip = count - LOG_SIZE;
count -= skip;
buf += skip;
w = subwrite(&logdevices[0], count, SELF, (vir_bytes) buf,0);
if(w > 0 && w < count)
subwrite(&logdevices[0], count-w, SELF, (vir_bytes) buf+w,0);
return;
}
/*===========================================================================*
* subread *
*===========================================================================*/
PRIVATE int
subread(struct logdevice *log, int count, int proc_nr,
vir_bytes user_vir, size_t offset)
{
char *buf;
int r;
if (count > log->log_size)
count = log->log_size;
if (log->log_read + count > LOG_SIZE)
count = LOG_SIZE - log->log_read;
buf = log->log_buffer + log->log_read;
if((r=sys_safecopyto(proc_nr, user_vir, offset,
(vir_bytes)buf, count, D)) != OK)
return r;
LOGINC(log->log_read, count);
log->log_size -= count;
return count;
}
/*===========================================================================*
* log_transfer *
*===========================================================================*/
PRIVATE int log_transfer(proc_nr, opcode, position, iov, nr_req)
int proc_nr; /* process doing the request */
int opcode; /* DEV_GATHER_S or DEV_SCATTER_S */
u64_t position; /* offset on device to read or write */
iovec_t *iov; /* pointer to read or write request vector */
unsigned nr_req; /* length of request vector */
{
/* Read or write one the driver's minor devices. */
unsigned count;
vir_bytes user_vir;
struct device *dv;
unsigned long dv_size;
int accumulated_read = 0;
struct logdevice *log;
static int f;
size_t vir_offset = 0;
if(log_device < 0 || log_device >= NR_DEVS)
return EIO;
/* Get minor device number and check for /dev/null. */
dv = &log_geom[log_device];
dv_size = cv64ul(dv->dv_size);
log = &logdevices[log_device];
while (nr_req > 0) {
/* How much to transfer and where to / from. */
count = iov->iov_size;
user_vir = iov->iov_addr;
switch (log_device) {
case MINOR_KLOG:
if (opcode == DEV_GATHER_S) {
if (log->log_proc_nr || count < 1) {
/* There's already someone hanging to read, or
* no real I/O requested.
*/
return(OK);
}
if (!log->log_size) {
if(accumulated_read)
return OK;
/* No data available; let caller block. */
log->log_proc_nr = proc_nr;
log->log_iosize = count;
log->log_user_vir_g = user_vir;
log->log_user_vir_offset = 0;
log->log_revive_alerted = 0;
/* Device_caller is a global in drivers library. */
log->log_source = device_caller;
#if LOG_DEBUG
printf("blocked %d (%d)\n",
log->log_source, log->log_proc_nr);
#endif
return(EDONTREPLY);
}
count = subread(log, count, proc_nr, user_vir, vir_offset);
if(count < 0) {
return count;
}
accumulated_read += count;
} else {
count = subwrite(log, count, proc_nr, user_vir, vir_offset);
if(count < 0)
return count;
}
break;
/* Unknown (illegal) minor device. */
default:
return(EINVAL);
}
/* Book the number of bytes transferred. */
vir_offset += count;
if ((iov->iov_size -= count) == 0) { iov++; nr_req--; vir_offset = 0; }
}
return(OK);
}
/*============================================================================*
* log_do_open *
*============================================================================*/
PRIVATE int log_do_open(dp, m_ptr)
struct driver *dp;
message *m_ptr;
{
if (log_prepare(m_ptr->DEVICE) == NIL_DEV) return(ENXIO);
return(OK);
}
/*============================================================================*
* log_geometry *
*============================================================================*/
PRIVATE void log_geometry(entry)
struct partition *entry;
{
/* take a page from the fake memory device geometry */
entry->heads = 64;
entry->sectors = 32;
entry->cylinders = div64u(log_geom[log_device].dv_size, SECTOR_SIZE) /
(entry->heads * entry->sectors);
}
/*============================================================================*
* log_cancel *
*============================================================================*/
PRIVATE int log_cancel(dp, m_ptr)
struct driver *dp;
message *m_ptr;
{
int d;
d = m_ptr->TTY_LINE;
if(d < 0 || d >= NR_DEVS)
return EINVAL;
logdevices[d].log_proc_nr = 0;
logdevices[d].log_revive_alerted = 0;
return(OK);
}
/*============================================================================*
* log_signal *
*============================================================================*/
PRIVATE void log_signal(dp, set)
struct driver *dp;
sigset_t *set;
{
if (sigismember(set, SIGKMESS)) {
do_new_kmess(SYSTEM);
}
}
/*============================================================================*
* log_other *
*============================================================================*/
PRIVATE int log_other(dp, m_ptr)
struct driver *dp;
message *m_ptr;
{
int r;
/* This function gets messages that the generic driver doesn't
* understand.
*/
if (is_notify(m_ptr->m_type)) {
switch (_ENDPOINT_P(m_ptr->m_source)) {
case TTY_PROC_NR:
do_new_kmess(m_ptr->m_source);
r = EDONTREPLY;
break;
default:
r = EINVAL;
break;
}
return r;
}
switch(m_ptr->m_type) {
case DIAGNOSTICS_OLD: {
r = do_diagnostics(m_ptr, 0);
break;
}
case ASYN_DIAGNOSTICS_OLD:
case DIAGNOSTICS_S_OLD:
r = do_diagnostics(m_ptr, 1);
break;
case DEV_STATUS: {
printf("log_other: unexpected DEV_STATUS request\n");
r = EDONTREPLY;
break;
}
default:
r = EINVAL;
break;
}
return r;
}
/*============================================================================*
* log_select *
*============================================================================*/
PRIVATE int log_select(dp, m_ptr)
struct driver *dp;
message *m_ptr;
{
int d, ready_ops = 0, ops = 0;
d = m_ptr->TTY_LINE;
if(d < 0 || d >= NR_DEVS) {
#if LOG_DEBUG
printf("line %d? EINVAL\n", d);
#endif
return EINVAL;
}
ops = m_ptr->IO_ENDPT & (SEL_RD|SEL_WR|SEL_ERR);
/* Read blocks when there is no log. */
if((m_ptr->IO_ENDPT & SEL_RD) && logdevices[d].log_size > 0) {
#if LOG_DEBUG
printf("log can read; size %d\n", logdevices[d].log_size);
#endif
ready_ops |= SEL_RD; /* writes never block */
}
/* Write never blocks. */
if(m_ptr->IO_ENDPT & SEL_WR) ready_ops |= SEL_WR;
/* Enable select calback if no operations were
* ready to go, but operations were requested,
* and notify was enabled.
*/
if((m_ptr->IO_ENDPT & SEL_NOTIFY) && ops && !ready_ops) {
logdevices[d].log_selected |= ops;
logdevices[d].log_select_proc = m_ptr->m_source;
#if LOG_DEBUG
printf("log setting selector.\n");
#endif
}
#if LOG_DEBUG
printf("log returning ops %d\n", ready_ops);
#endif
return(ready_ops);
}