minix/drivers/log/log.c
Tomas Hruby 72b7abd1a1 VFS - no CANCEL for async non-blocking operations
- if an operation (R, W, IOCTL) is non blocking, a flag is set
  and sent to the device.

- nothing changes for sync devices

- asyn devices should reply asap if an operation is non-blocking.
  We must trust the devices, but we had to trust them anyway to
  reply to CANCEL correctly

- we safe sending CANCEL commands to asyn devices. This greatly
  simplifies the protocol. Asynchronous devices can always reply
  when a reply is ready and do not need to deal with other
  situations

- currently, none of our drivers use the flags since they drive
  virtual devices which do not block
2012-03-02 15:44:48 +00:00

451 lines
13 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( struct device *log_prepare, (dev_t device) );
FORWARD _PROTOTYPE( int log_transfer, (endpoint_t endpt, int opcode,
u64_t position, iovec_t *iov, unsigned int nr_req,
endpoint_t user_endpt, unsigned int flags) );
FORWARD _PROTOTYPE( int log_do_open, (message *m_ptr) );
FORWARD _PROTOTYPE( int log_cancel, (message *m_ptr) );
FORWARD _PROTOTYPE( int log_select, (message *m_ptr) );
FORWARD _PROTOTYPE( int log_other, (message *m_ptr) );
FORWARD _PROTOTYPE( int subread, (struct logdevice *log, int count,
endpoint_t endpt, cp_grant_id_t grant, size_t) );
/* Entry points to this driver. */
PRIVATE struct chardriver log_dtab = {
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 */
nop_alarm, /* no alarm */
log_cancel, /* CANCEL request */
log_select, /* DEV_SELECT request */
log_other /* Unrecognized messages */
};
/* SEF functions and variables. */
FORWARD _PROTOTYPE( void sef_local_startup, (void) );
FORWARD _PROTOTYPE( int sef_cb_init_fresh, (int type, sef_init_info_t *info) );
EXTERN _PROTOTYPE( int 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) );
FORWARD _PROTOTYPE( void sef_cb_signal_handler, (int signo) );
/*===========================================================================*
* main *
*===========================================================================*/
PUBLIC int main(void)
{
/* SEF local startup. */
sef_local_startup();
/* Call the generic receive loop. */
chardriver_task(&log_dtab, CHARDRIVER_ASYNC);
return(OK);
}
/*===========================================================================*
* sef_local_startup *
*===========================================================================*/
PRIVATE void sef_local_startup()
{
/* Register init callbacks. */
sef_setcb_init_fresh(sef_cb_init_fresh);
sef_setcb_init_lu(sef_cb_init_fresh);
sef_setcb_init_restart(sef_cb_init_fresh);
/* 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);
/* Register signal callbacks. */
sef_setcb_signal_handler(sef_cb_signal_handler);
/* Let SEF perform startup. */
sef_startup();
}
/*===========================================================================*
* sef_cb_init_fresh *
*===========================================================================*/
PRIVATE int sef_cb_init_fresh(int UNUSED(type), sef_init_info_t *UNUSED(info))
{
/* Initialize the log driver. */
int i;
/* 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_source = NONE;
logdevices[i].log_revive_alerted = 0;
}
return(OK);
}
/*===========================================================================*
* sef_cb_signal_handler *
*===========================================================================*/
PRIVATE void sef_cb_signal_handler(int signo)
{
/* Only check for a pending message from the kernel, ignore anything else. */
if (signo != SIGKMESS) return;
do_new_kmess();
}
/*===========================================================================*
* log_prepare *
*===========================================================================*/
PRIVATE struct device *log_prepare(dev_t device)
{
/* Prepare for I/O on a device: check if the minor device number is ok. */
if (device >= NR_DEVS) return(NULL);
log_device = (int) device;
return(&log_geom[device]);
}
/*===========================================================================*
* subwrite *
*===========================================================================*/
PRIVATE int
subwrite(struct logdevice *log, int count, endpoint_t endpt,
cp_grant_id_t grant, size_t offset, char *localbuf)
{
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(localbuf != NULL) {
memcpy(buf, localbuf, count);
}
else {
if((r=sys_safecopyfrom(endpt, grant, 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_source != NONE &&
!log->log_revive_alerted) {
/* Someone who was suspended on read can now
* be revived.
*/
log->log_status = subread(log, log->log_iosize,
log->log_source, log->log_user_grant,
log->log_user_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_grant;
r= send(log->log_source, &m);
if (r != OK)
{
printf("log`subwrite: send to %d failed: %d\n",
log->log_source, r);
}
log->log_source = NONE;
}
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, GRANT_INVALID, 0, buf);
if(w > 0 && w < count)
subwrite(&logdevices[0], count-w, SELF, GRANT_INVALID, 0,
buf + w);
return;
}
/*===========================================================================*
* subread *
*===========================================================================*/
PRIVATE int
subread(struct logdevice *log, int count, endpoint_t endpt,
cp_grant_id_t grant, 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(endpt, grant, 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(
endpoint_t endpt, /* endpoint of grant owner */
int opcode, /* DEV_GATHER_S or DEV_SCATTER_S */
u64_t UNUSED(position), /* offset on device to read or write */
iovec_t *iov, /* pointer to read or write request vector */
unsigned int nr_req, /* length of request vector */
endpoint_t user_endpt, /* endpoint of user process */
unsigned int UNUSED(flags)
)
{
/* Read or write one the driver's minor devices. */
int count;
cp_grant_id_t grant;
int accumulated_read = 0;
struct logdevice *log;
size_t vir_offset = 0;
if(log_device < 0 || log_device >= NR_DEVS)
return EIO;
/* Get minor device number and check for /dev/null. */
log = &logdevices[log_device];
while (nr_req > 0) {
/* How much to transfer and where to / from. */
count = iov->iov_size;
grant = iov->iov_addr;
switch (log_device) {
case MINOR_KLOG:
if (opcode == DEV_GATHER_S) {
if (log->log_source != NONE || 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_source = endpt;
log->log_iosize = count;
log->log_user_grant = grant;
log->log_user_offset = 0;
log->log_revive_alerted = 0;
log->log_proc_nr = user_endpt;
#if LOG_DEBUG
printf("blocked %d (%d)\n",
log->log_source, log->log_proc_nr);
#endif
return(EDONTREPLY);
}
count = subread(log, count, endpt, grant, vir_offset);
if(count < 0) {
return count;
}
accumulated_read += count;
} else {
count = subwrite(log, count, endpt, grant, vir_offset, NULL);
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(message *m_ptr)
{
if (log_prepare(m_ptr->DEVICE) == NULL) return(ENXIO);
return(OK);
}
/*============================================================================*
* log_cancel *
*============================================================================*/
PRIVATE int log_cancel(message *m_ptr)
{
int d;
d = m_ptr->TTY_LINE;
if(d < 0 || d >= NR_DEVS)
return EINVAL;
logdevices[d].log_proc_nr = NONE;
logdevices[d].log_revive_alerted = 0;
return(OK);
}
/*============================================================================*
* log_other *
*============================================================================*/
PRIVATE int log_other(message *m_ptr)
{
int r;
/* This function gets messages that the generic driver doesn't
* understand.
*/
if (is_notify(m_ptr->m_type)) {
return EINVAL;
}
switch(m_ptr->m_type) {
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(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->USER_ENDPT & (SEL_RD|SEL_WR|SEL_ERR);
/* Read blocks when there is no log. */
if((m_ptr->USER_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->USER_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->USER_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);
}