179 lines
4.6 KiB
C
179 lines
4.6 KiB
C
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#include <minix/config.h>
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#include <assert.h>
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#include <sys/types.h>
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#include <minix/const.h>
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#include <minix/type.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <minix/syslib.h>
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#include <minix/sysutil.h>
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#include <minix/sys_config.h>
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#include <limits.h>
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#include <errno.h>
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#define ASYN_NR (2*_NR_PROCS)
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static asynmsg_t msgtable[ASYN_NR];
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static int first_slot = 0, next_slot = 0;
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static int initialized = 0;
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#define DEBUG 0
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/*===========================================================================*
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* asynsend3 *
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*===========================================================================*/
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int asynsend3(dst, mp, fl)
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endpoint_t dst;
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message *mp;
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int fl;
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{
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int i, r, src_ind, dst_ind;
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unsigned flags;
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static int inside = 0;
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int len, needack = 0;
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/* Debug printf() causes asynchronous sends? */
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if (inside) /* Panic will not work either then, so exit */
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exit(1);
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inside = 1;
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if(!initialized) {
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/* Initialize table by marking all entries empty */
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for (i = 0; i < ASYN_NR; i++) msgtable[i].flags = AMF_EMPTY;
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initialized = 1;
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}
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/* Update first_slot. That is, find the first not-completed slot by the
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* kernel since the last time we sent this table (e.g., the receiving end of
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* the message wasn't ready yet).
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*/
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for (; first_slot < next_slot; first_slot++) {
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flags = msgtable[first_slot].flags;
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if ((flags & (AMF_VALID|AMF_DONE)) == (AMF_VALID|AMF_DONE)) {
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/* Marked in use by us (VALID) and processed by the kernel */
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if (msgtable[first_slot].result != OK) {
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#if DEBUG
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printf("asynsend: found entry %d with error %d\n",
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first_slot, msgtable[first_slot].result);
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#endif
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needack = (flags & (AMF_NOTIFY|AMF_NOTIFY_ERR));
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}
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continue;
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}
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if (flags != AMF_EMPTY)
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/* Found first not-completed table entry */
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break;
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}
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/* Reset to the beginning of the table when all messages are completed */
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if (first_slot >= next_slot && !needack)
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next_slot = first_slot = 0;
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/* Can the table handle one more message? */
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if (next_slot >= ASYN_NR) {
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/* We're full; tell the kernel to stop processing for now */
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if ((r = ipc_senda(NULL, 0)) != OK)
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panic("asynsend: ipc_senda failed: %d", r);
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/* Move all unprocessed messages to the beginning */
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dst_ind = 0;
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for (src_ind = first_slot; src_ind < next_slot; src_ind++) {
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flags = msgtable[src_ind].flags;
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/* Skip empty entries */
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if (flags == AMF_EMPTY) continue;
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/* and completed entries only if result is OK or if error
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* doesn't need to be acknowledged */
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if ((flags & (AMF_VALID|AMF_DONE)) == (AMF_VALID|AMF_DONE)) {
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if (msgtable[src_ind].result == OK)
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continue;
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else {
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#if DEBUG
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printf(
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"asynsend: found entry %d with error %d\n",
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src_ind, msgtable[src_ind].result);
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#endif
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if (!(flags & (AMF_NOTIFY|AMF_NOTIFY_ERR)))
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/* Don't need to ack this error */
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continue;
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}
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}
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/* Copy/move in use entry */
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#if DEBUG
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printf("asynsend: copying entry %d to %d\n", src_ind, dst_ind);
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#endif
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if (src_ind != dst_ind) msgtable[dst_ind] = msgtable[src_ind];
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dst_ind++;
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}
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/* Mark unused entries empty */
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for (i = dst_ind; i < ASYN_NR; i++) msgtable[i].flags = AMF_EMPTY;
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first_slot = 0;
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next_slot = dst_ind;
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if (next_slot >= ASYN_NR) /* Cleanup failed */
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panic("asynsend: msgtable full");
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}
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fl |= AMF_VALID; /* Mark in use */
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msgtable[next_slot].dst = dst;
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msgtable[next_slot].msg = *mp;
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msgtable[next_slot].flags = fl; /* Has to be last. The kernel
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* scans this table while we
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* are sleeping.
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*/
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next_slot++;
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assert(next_slot >= first_slot);
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len = next_slot - first_slot;
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assert(first_slot + len <= ASYN_NR);
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assert(len >= 0);
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inside = 0;
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/* Tell the kernel to rescan the table */
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return ipc_senda(&msgtable[first_slot], len);
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}
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/*===========================================================================*
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* asyn_geterror *
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*===========================================================================*/
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int asyn_geterror(endpoint_t *dst, message *msg, int *err)
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{
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int src_ind, flags, result;
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if (!initialized) return(0);
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for (src_ind = 0; src_ind < next_slot; src_ind++) {
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flags = msgtable[src_ind].flags;
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result = msgtable[src_ind].result;
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/* Find a message that has been completed with an error */
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if ((flags & (AMF_VALID|AMF_DONE)) == (AMF_VALID|AMF_DONE)) {
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if (result != OK && (flags & (AMF_NOTIFY|AMF_NOTIFY_ERR))) {
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/* Found one */
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if (dst != NULL) *dst = msgtable[src_ind].dst;
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if (msg != NULL) *msg = msgtable[src_ind].msg;
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if (err != NULL) *err = result;
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/* Acknowledge error so it can be cleaned up upon next
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* asynsend */
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msgtable[src_ind].result = OK;
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return(1);
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}
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}
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}
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return(0);
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}
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