/* This file contains essentially all of the process and message handling. * Together with "mpx.s" it forms the lowest layer of the MINIX kernel. * There is one entry point from the outside: * * sys_call: a system call, i.e., the kernel is trapped with an INT * * As well as several entry points used from the interrupt and task level: * * lock_notify: notify a process of a system event * lock_send: send a message to a process * lock_enqueue: put a process on one of the scheduling queues * lock_dequeue: remove a process from the scheduling queues * * Changes: * Aug 19, 2005 rewrote scheduling code (Jorrit N. Herder) * Jul 25, 2005 rewrote system call handling (Jorrit N. Herder) * May 26, 2005 rewrote message passing functions (Jorrit N. Herder) * May 24, 2005 new notification system call (Jorrit N. Herder) * Oct 28, 2004 nonblocking send and receive calls (Jorrit N. Herder) * * The code here is critical to make everything work and is important for the * overall performance of the system. A large fraction of the code deals with * list manipulation. To make this both easy to understand and fast to execute * pointer pointers are used throughout the code. Pointer pointers prevent * exceptions for the head or tail of a linked list. * * node_t *queue, *new_node; // assume these as global variables * node_t **xpp = &queue; // get pointer pointer to head of queue * while (*xpp != NULL) // find last pointer of the linked list * xpp = &(*xpp)->next; // get pointer to next pointer * *xpp = new_node; // now replace the end (the NULL pointer) * new_node->next = NULL; // and mark the new end of the list * * For example, when adding a new node to the end of the list, one normally * makes an exception for an empty list and looks up the end of the list for * nonempty lists. As shown above, this is not required with pointer pointers. */ #include #include #include #include "debug.h" #include "kernel.h" #include "proc.h" #include #include #include /* Scheduling and message passing functions. The functions are available to * other parts of the kernel through lock_...(). The lock temporarily disables * interrupts to prevent race conditions. */ FORWARD _PROTOTYPE( int mini_send, (struct proc *caller_ptr, int dst_e, message *m_ptr, unsigned flags)); FORWARD _PROTOTYPE( int mini_receive, (struct proc *caller_ptr, int src, message *m_ptr, unsigned flags)); FORWARD _PROTOTYPE( int mini_notify, (struct proc *caller_ptr, int dst)); FORWARD _PROTOTYPE( int mini_senda, (struct proc *caller_ptr, asynmsg_t *table, size_t size)); FORWARD _PROTOTYPE( int deadlock, (int function, register struct proc *caller, int src_dst)); FORWARD _PROTOTYPE( int try_async, (struct proc *caller_ptr)); FORWARD _PROTOTYPE( int try_one, (struct proc *src_ptr, struct proc *dst_ptr)); FORWARD _PROTOTYPE( void enqueue, (struct proc *rp)); FORWARD _PROTOTYPE( void dequeue, (struct proc *rp)); FORWARD _PROTOTYPE( void sched, (struct proc *rp, int *queue, int *front)); FORWARD _PROTOTYPE( void pick_proc, (void)); #define BuildMess(m_ptr, src, dst_ptr) \ (m_ptr)->m_source = proc_addr(src)->p_endpoint; \ (m_ptr)->m_type = NOTIFY_FROM(src); \ (m_ptr)->NOTIFY_TIMESTAMP = get_uptime(); \ switch (src) { \ case HARDWARE: \ (m_ptr)->NOTIFY_ARG = priv(dst_ptr)->s_int_pending; \ priv(dst_ptr)->s_int_pending = 0; \ break; \ case SYSTEM: \ (m_ptr)->NOTIFY_ARG = priv(dst_ptr)->s_sig_pending; \ priv(dst_ptr)->s_sig_pending = 0; \ break; \ } #define CopyMess(s,sp,sm,dp,dm) \ cp_mess(proc_addr(s)->p_endpoint, \ (sp)->p_memmap[D].mem_phys, \ (vir_bytes)sm, (dp)->p_memmap[D].mem_phys, (vir_bytes)dm) /*===========================================================================* * sys_call * *===========================================================================*/ PUBLIC int sys_call(call_nr, src_dst_e, m_ptr, bit_map) int call_nr; /* system call number and flags */ int src_dst_e; /* src to receive from or dst to send to */ message *m_ptr; /* pointer to message in the caller's space */ long bit_map; /* notification event set or flags */ { /* System calls are done by trapping to the kernel with an INT instruction. * The trap is caught and sys_call() is called to send or receive a message * (or both). The caller is always given by 'proc_ptr'. */ register struct proc *caller_ptr = proc_ptr; /* get pointer to caller */ int mask_entry; /* bit to check in send mask */ int group_size; /* used for deadlock check */ int result; /* the system call's result */ int src_dst_p; /* Process slot number */ vir_clicks vlo, vhi; /* virtual clicks containing message to send */ #if 1 if (RTS_ISSET(caller_ptr, SLOT_FREE)) { kprintf("called by the dead?!?\n"); return EINVAL; } #endif /* Check destination. SENDA is special because its argument is a table and * not a single destination. RECEIVE is the only call that accepts ANY (in * addition to a real endpoint). The other calls (SEND, SENDNB, SENDREC, * and NOTIFY) require an endpoint to corresponds to a process. In addition, * it is necessary to check whether a process is allow to send to a given * destination. For SENDREC we check s_ipc_sendrec, and for SEND, SENDNB, * and NOTIFY we check s_ipc_to. */ if (call_nr == SENDA) { /* No destination argument */ } else if (src_dst_e == ANY) { if (call_nr != RECEIVE) { #if DEBUG_ENABLE_IPC_WARNINGS kprintf("sys_call: trap %d by %d with bad endpoint %d\n", call_nr, proc_nr(caller_ptr), src_dst_e); #endif return EINVAL; } src_dst_p = src_dst_e; } else { /* Require a valid source and/or destination process. */ if(!isokendpt(src_dst_e, &src_dst_p)) { if (src_dst_e == 0) panic("sys_call: no PM", NO_NUM); #if DEBUG_ENABLE_IPC_WARNINGS kprintf("sys_call: trap %d by %d with bad endpoint %d\n", call_nr, proc_nr(caller_ptr), src_dst_e); #endif return EDEADSRCDST; } /* If the call is to send to a process, i.e., for SEND, SENDNB, * SENDREC or NOTIFY, verify that the caller is allowed to send to * the given destination. */ if (call_nr == SENDREC) { if (! get_sys_bit(priv(caller_ptr)->s_ipc_sendrec, nr_to_id(src_dst_p))) { #if DEBUG_ENABLE_IPC_WARNINGS kprintf( "sys_call: ipc sendrec mask denied trap %d from %d to %d\n", call_nr, proc_nr(caller_ptr), src_dst_p); #endif return(ECALLDENIED); /* call denied by ipc mask */ } } else if (call_nr == SEND || call_nr == SENDNB || call_nr == NOTIFY) { if (! get_sys_bit(priv(caller_ptr)->s_ipc_to, nr_to_id(src_dst_p))) { #if DEBUG_ENABLE_IPC_WARNINGS kprintf( "sys_call: ipc mask denied trap %d from %d to %d\n", call_nr, proc_nr(caller_ptr), src_dst_p); #endif return(ECALLDENIED); /* call denied by ipc mask */ } } } /* Only allow non-negative call_nr values less than 32 */ if (call_nr < 0 || call_nr >= 32) { #if DEBUG_ENABLE_IPC_WARNINGS kprintf("sys_call: trap %d not allowed, caller %d, src_dst %d\n", call_nr, proc_nr(caller_ptr), src_dst_p); #endif return(ETRAPDENIED); /* trap denied by mask or kernel */ } /* Check if the process has privileges for the requested call. Calls to the * kernel may only be SENDREC, because tasks always reply and may not block * if the caller doesn't do receive(). */ if (!(priv(caller_ptr)->s_trap_mask & (1 << call_nr))) { #if DEBUG_ENABLE_IPC_WARNINGS kprintf("sys_call: trap %d not allowed, caller %d, src_dst %d\n", call_nr, proc_nr(caller_ptr), src_dst_p); #endif return(ETRAPDENIED); /* trap denied by mask or kernel */ } #if 0 if ((iskerneln(src_dst_p) && _function != SENDREC && _function != RECEIVE)) { #if DEBUG_ENABLE_IPC_WARNINGS kprintf("sys_call: trap %d not allowed, caller %d, src_dst %d\n", function, proc_nr(caller_ptr), src_dst); #endif return(ETRAPDENIED); /* trap denied by mask or kernel */ } #endif /* If the call involves a message buffer, i.e., for SEND, SENDNB, SENDREC, * or RECEIVE, check the message pointer. This check allows a message to be * anywhere in data or stack or gap. It will have to be made more elaborate * for machines which don't have the gap mapped. */ if (call_nr == SEND || call_nr == SENDNB || call_nr == SENDREC || call_nr == RECEIVE) { vlo = (vir_bytes) m_ptr >> CLICK_SHIFT; vhi = ((vir_bytes) m_ptr + MESS_SIZE - 1) >> CLICK_SHIFT; if (vlo < caller_ptr->p_memmap[D].mem_vir || vlo > vhi || vhi >= caller_ptr->p_memmap[S].mem_vir + caller_ptr->p_memmap[S].mem_len) { #if DEBUG_ENABLE_IPC_WARNINGS kprintf( "sys_call: invalid message pointer, trap %d, caller %d\n", call_nr, proc_nr(caller_ptr)); #endif return(EFAULT); /* invalid message pointer */ } } /* Check for a possible deadlock for blocking SEND(REC) and RECEIVE. */ if (call_nr == SEND || call_nr == SENDREC || call_nr == RECEIVE) { if (group_size = deadlock(call_nr, caller_ptr, src_dst_p)) { #if DEBUG_ENABLE_IPC_WARNINGS kprintf("sys_call: trap %d from %d to %d deadlocked, group size %d\n", call_nr, proc_nr(caller_ptr), src_dst_p, group_size); #endif return(ELOCKED); } } /* Now check if the call is known and try to perform the request. The only * system calls that exist in MINIX are sending and receiving messages. * - SENDREC: combines SEND and RECEIVE in a single system call * - SEND: sender blocks until its message has been delivered * - RECEIVE: receiver blocks until an acceptable message has arrived * - NOTIFY: asynchronous call; deliver notification or mark pending * - SENDNB: nonblocking send * - SENDA: list of asynchronous send requests */ switch(call_nr) { case SENDREC: /* A flag is set so that notifications cannot interrupt SENDREC. */ caller_ptr->p_misc_flags |= REPLY_PENDING; /* fall through */ case SEND: result = mini_send(caller_ptr, src_dst_e, m_ptr, 0 /*flags*/); if (call_nr == SEND || result != OK) break; /* done, or SEND failed */ /* fall through for SENDREC */ case RECEIVE: if (call_nr == RECEIVE) caller_ptr->p_misc_flags &= ~REPLY_PENDING; result = mini_receive(caller_ptr, src_dst_e, m_ptr, 0 /*flags*/); break; case NOTIFY: result = mini_notify(caller_ptr, src_dst_p); break; case SENDNB: result = mini_send(caller_ptr, src_dst_e, m_ptr, NON_BLOCKING); break; case SENDA: result = mini_senda(caller_ptr, (asynmsg_t *)m_ptr, (size_t)src_dst_e); break; default: result = EBADCALL; /* illegal system call */ } /* Now, return the result of the system call to the caller. */ return(result); } /*===========================================================================* * deadlock * *===========================================================================*/ PRIVATE int deadlock(function, cp, src_dst) int function; /* trap number */ register struct proc *cp; /* pointer to caller */ int src_dst; /* src or dst process */ { /* Check for deadlock. This can happen if 'caller_ptr' and 'src_dst' have * a cyclic dependency of blocking send and receive calls. The only cyclic * depency that is not fatal is if the caller and target directly SEND(REC) * and RECEIVE to each other. If a deadlock is found, the group size is * returned. Otherwise zero is returned. */ register struct proc *xp; /* process pointer */ int group_size = 1; /* start with only caller */ int trap_flags; while (src_dst != ANY) { /* check while process nr */ int src_dst_e; xp = proc_addr(src_dst); /* follow chain of processes */ group_size ++; /* extra process in group */ /* Check whether the last process in the chain has a dependency. If it * has not, the cycle cannot be closed and we are done. */ if (RTS_ISSET(xp, RECEIVING)) { /* xp has dependency */ if(xp->p_getfrom_e == ANY) src_dst = ANY; else okendpt(xp->p_getfrom_e, &src_dst); } else if (RTS_ISSET(xp, SENDING)) { /* xp has dependency */ okendpt(xp->p_sendto_e, &src_dst); } else { return(0); /* not a deadlock */ } /* Now check if there is a cyclic dependency. For group sizes of two, * a combination of SEND(REC) and RECEIVE is not fatal. Larger groups * or other combinations indicate a deadlock. */ if (src_dst == proc_nr(cp)) { /* possible deadlock */ if (group_size == 2) { /* caller and src_dst */ /* The function number is magically converted to flags. */ if ((xp->p_rts_flags ^ (function << 2)) & SENDING) { return(0); /* not a deadlock */ } } return(group_size); /* deadlock found */ } } return(0); /* not a deadlock */ } /*===========================================================================* * mini_send * *===========================================================================*/ PRIVATE int mini_send(caller_ptr, dst_e, m_ptr, flags) register struct proc *caller_ptr; /* who is trying to send a message? */ int dst_e; /* to whom is message being sent? */ message *m_ptr; /* pointer to message buffer */ unsigned flags; /* system call flags */ { /* Send a message from 'caller_ptr' to 'dst'. If 'dst' is blocked waiting * for this message, copy the message to it and unblock 'dst'. If 'dst' is * not waiting at all, or is waiting for another source, queue 'caller_ptr'. */ register struct proc *dst_ptr; register struct proc **xpp; int dst_p; dst_p = _ENDPOINT_P(dst_e); dst_ptr = proc_addr(dst_p); if (RTS_ISSET(dst_ptr, NO_ENDPOINT)) return EDSTDIED; /* Check if 'dst' is blocked waiting for this message. The destination's * SENDING flag may be set when its SENDREC call blocked while sending. */ if ( (RTS_ISSET(dst_ptr, RECEIVING) && !RTS_ISSET(dst_ptr, SENDING)) && (dst_ptr->p_getfrom_e == ANY || dst_ptr->p_getfrom_e == caller_ptr->p_endpoint)) { /* Destination is indeed waiting for this message. */ CopyMess(caller_ptr->p_nr, caller_ptr, m_ptr, dst_ptr, dst_ptr->p_messbuf); RTS_UNSET(dst_ptr, RECEIVING); } else if ( ! (flags & NON_BLOCKING)) { /* Destination is not waiting. Block and dequeue caller. */ caller_ptr->p_messbuf = m_ptr; RTS_SET(caller_ptr, SENDING); caller_ptr->p_sendto_e = dst_e; /* Process is now blocked. Put in on the destination's queue. */ xpp = &dst_ptr->p_caller_q; /* find end of list */ while (*xpp != NIL_PROC) xpp = &(*xpp)->p_q_link; *xpp = caller_ptr; /* add caller to end */ caller_ptr->p_q_link = NIL_PROC; /* mark new end of list */ } else { return(ENOTREADY); } return(OK); } /*===========================================================================* * mini_receive * *===========================================================================*/ PRIVATE int mini_receive(caller_ptr, src_e, m_ptr, flags) register struct proc *caller_ptr; /* process trying to get message */ int src_e; /* which message source is wanted */ message *m_ptr; /* pointer to message buffer */ unsigned flags; /* system call flags */ { /* A process or task wants to get a message. If a message is already queued, * acquire it and deblock the sender. If no message from the desired source * is available block the caller, unless the flags don't allow blocking. */ register struct proc **xpp; register struct notification **ntf_q_pp; message m; int bit_nr; sys_map_t *map; bitchunk_t *chunk; int i, r, src_id, src_proc_nr, src_p; if(src_e == ANY) src_p = ANY; else { okendpt(src_e, &src_p); if (RTS_ISSET(proc_addr(src_p), NO_ENDPOINT)) return ESRCDIED; } /* Check to see if a message from desired source is already available. * The caller's SENDING flag may be set if SENDREC couldn't send. If it is * set, the process should be blocked. */ if (!RTS_ISSET(caller_ptr, SENDING)) { /* Check if there are pending notifications, except for SENDREC. */ if (! (caller_ptr->p_misc_flags & REPLY_PENDING)) { map = &priv(caller_ptr)->s_notify_pending; for (chunk=&map->chunk[0]; chunk<&map->chunk[NR_SYS_CHUNKS]; chunk++) { /* Find a pending notification from the requested source. */ if (! *chunk) continue; /* no bits in chunk */ for (i=0; ! (*chunk & (1<chunk[0]) * BITCHUNK_BITS + i; if (src_id >= NR_SYS_PROCS) break; /* out of range */ src_proc_nr = id_to_nr(src_id); /* get source proc */ #if DEBUG_ENABLE_IPC_WARNINGS if(src_proc_nr == NONE) { kprintf("mini_receive: sending notify from NONE\n"); } #endif if (src_e!=ANY && src_p != src_proc_nr) continue;/* source not ok */ *chunk &= ~(1 << i); /* no longer pending */ /* Found a suitable source, deliver the notification message. */ BuildMess(&m, src_proc_nr, caller_ptr); /* assemble message */ CopyMess(src_proc_nr, proc_addr(HARDWARE), &m, caller_ptr, m_ptr); return(OK); /* report success */ } } /* Check caller queue. Use pointer pointers to keep code simple. */ xpp = &caller_ptr->p_caller_q; while (*xpp != NIL_PROC) { if (src_e == ANY || src_p == proc_nr(*xpp)) { #if 1 if (RTS_ISSET(*xpp, SLOT_FREE)) { kprintf("listening to the dead?!?\n"); return EINVAL; } #endif /* Found acceptable message. Copy it and update status. */ CopyMess((*xpp)->p_nr, *xpp, (*xpp)->p_messbuf, caller_ptr, m_ptr); RTS_UNSET(*xpp, SENDING); *xpp = (*xpp)->p_q_link; /* remove from queue */ return(OK); /* report success */ } xpp = &(*xpp)->p_q_link; /* proceed to next */ } if (caller_ptr->p_misc_flags & MF_ASYNMSG) { if (src_e != ANY) { #if 0 kprintf("mini_receive: should try async from %d\n", src_e); #endif r= EAGAIN; } else { caller_ptr->p_messbuf = m_ptr; r= try_async(caller_ptr); } if (r == OK) return OK; /* Got a message */ } } /* No suitable message is available or the caller couldn't send in SENDREC. * Block the process trying to receive, unless the flags tell otherwise. */ if ( ! (flags & NON_BLOCKING)) { caller_ptr->p_getfrom_e = src_e; caller_ptr->p_messbuf = m_ptr; RTS_SET(caller_ptr, RECEIVING); return(OK); } else { return(ENOTREADY); } } /*===========================================================================* * mini_notify * *===========================================================================*/ PRIVATE int mini_notify(caller_ptr, dst) register struct proc *caller_ptr; /* sender of the notification */ int dst; /* which process to notify */ { register struct proc *dst_ptr = proc_addr(dst); int src_id; /* source id for late delivery */ message m; /* the notification message */ /* Check to see if target is blocked waiting for this message. A process * can be both sending and receiving during a SENDREC system call. */ if ( (RTS_ISSET(dst_ptr, RECEIVING) && !RTS_ISSET(dst_ptr, SENDING)) && ! (dst_ptr->p_misc_flags & REPLY_PENDING) && (dst_ptr->p_getfrom_e == ANY || dst_ptr->p_getfrom_e == caller_ptr->p_endpoint)) { /* Destination is indeed waiting for a message. Assemble a notification * message and deliver it. Copy from pseudo-source HARDWARE, since the * message is in the kernel's address space. */ BuildMess(&m, proc_nr(caller_ptr), dst_ptr); CopyMess(proc_nr(caller_ptr), proc_addr(HARDWARE), &m, dst_ptr, dst_ptr->p_messbuf); RTS_UNSET(dst_ptr, RECEIVING); return(OK); } /* Destination is not ready to receive the notification. Add it to the * bit map with pending notifications. Note the indirectness: the system id * instead of the process number is used in the pending bit map. */ src_id = priv(caller_ptr)->s_id; set_sys_bit(priv(dst_ptr)->s_notify_pending, src_id); return(OK); } /*===========================================================================* * mini_senda * *===========================================================================*/ PRIVATE int mini_senda(caller_ptr, table, size) struct proc *caller_ptr; asynmsg_t *table; size_t size; { int i, dst_p, done, do_notify; unsigned flags; phys_bytes tab_phys; struct proc *dst_ptr; struct priv *privp; message *m_ptr; asynmsg_t tabent; privp= priv(caller_ptr); if (!(privp->s_flags & SYS_PROC)) { kprintf( "mini_senda: warning caller has no privilege structure\n"); return EPERM; } /* Clear table */ privp->s_asyntab= -1; privp->s_asynsize= 0; if (size == 0) { /* Nothing to do, just return */ return OK; } /* Limit size to something reasonable. An arbitrary choice is 16 * times the number of process table entries. */ if (size > 16*(NR_TASKS + NR_PROCS)) return EDOM; /* Map table */ tab_phys= umap_local(caller_ptr, D, (vir_bytes)table, size*sizeof(table[0])); if (tab_phys == 0) { kprintf("mini_senda: got bad table pointer/size\n"); return EFAULT; } /* Scan the table */ do_notify= FALSE; done= TRUE; for (i= 0; ip_rts_flags & NO_ENDPOINT) { tabent.result= EDSTDIED; phys_copy(vir2phys(&tabent.result), tab_phys + i*sizeof(table[0]) + offsetof(struct asynmsg, result), sizeof(tabent.result)); tabent.flags= flags | AMF_DONE; phys_copy(vir2phys(&tabent.flags), tab_phys + i*sizeof(table[0]) + offsetof(struct asynmsg, flags), sizeof(tabent.flags)); if (flags & AMF_NOTIFY) do_notify= TRUE; continue; } /* Check if 'dst' is blocked waiting for this message. The * destination's SENDING flag may be set when its SENDREC call * blocked while sending. */ if ( (dst_ptr->p_rts_flags & (RECEIVING | SENDING)) == RECEIVING && (dst_ptr->p_getfrom_e == ANY || dst_ptr->p_getfrom_e == caller_ptr->p_endpoint)) { /* Destination is indeed waiting for this message. */ m_ptr= &table[i].msg; /* Note: pointer in the * caller's address space. */ CopyMess(caller_ptr->p_nr, caller_ptr, m_ptr, dst_ptr, dst_ptr->p_messbuf); if ((dst_ptr->p_rts_flags &= ~RECEIVING) == 0) enqueue(dst_ptr); tabent.result= OK; phys_copy(vir2phys(&tabent.result), tab_phys + i*sizeof(table[0]) + offsetof(struct asynmsg, result), sizeof(tabent.result)); tabent.flags= flags | AMF_DONE; phys_copy(vir2phys(&tabent.flags), tab_phys + i*sizeof(table[0]) + offsetof(struct asynmsg, flags), sizeof(tabent.flags)); if (flags & AMF_NOTIFY) do_notify= 1; continue; } else { /* Should inform receiver that something is pending */ dst_ptr->p_misc_flags |= MF_ASYNMSG; done= FALSE; continue; } } if (do_notify) kprintf("mini_senda: should notifiy caller\n"); if (!done) { privp->s_asyntab= (vir_bytes)table; privp->s_asynsize= size; } return OK; } /*===========================================================================* * try_async * *===========================================================================*/ PRIVATE int try_async(caller_ptr) struct proc *caller_ptr; { int r; struct priv *privp; struct proc *src_ptr; /* Try all privilege structures */ for (privp = BEG_PRIV_ADDR; privp < END_PRIV_ADDR; ++privp) { if (privp->s_proc_nr == NONE || privp->s_id == USER_PRIV_ID) continue; if (privp->s_asynsize == 0) continue; #if 0 kprintf("try_async: found asyntable for proc %d\n", privp->s_proc_nr); #endif src_ptr= proc_addr(privp->s_proc_nr); r= try_one(src_ptr, caller_ptr); if (r == OK) return r; } /* Nothing found, clear MF_ASYNMSG */ caller_ptr->p_misc_flags &= ~MF_ASYNMSG; return ESRCH; } /*===========================================================================* * try_one * *===========================================================================*/ PRIVATE int try_one(src_ptr, dst_ptr) struct proc *src_ptr; struct proc *dst_ptr; { int i, do_notify, done; unsigned flags; size_t size; endpoint_t dst_e; phys_bytes tab_phys; asynmsg_t *table_ptr; message *m_ptr; struct priv *privp; asynmsg_t tabent; privp= priv(src_ptr); size= privp->s_asynsize; dst_e= dst_ptr->p_endpoint; /* Map table */ tab_phys= umap_local(src_ptr, D, privp->s_asyntab, size*sizeof(tabent)); if (tab_phys == 0) { kprintf("try_one: got bad table pointer/size\n"); privp->s_asynsize= 0; return EFAULT; } /* Scan the table */ do_notify= FALSE; done= TRUE; for (i= 0; is_asynsize= 0; return EINVAL; } /* Skip entry is AMF_DONE is already set */ if (flags & AMF_DONE) { continue; } /* Clear done. We are done when all entries are either empty * or done at the start of the call. */ done= FALSE; /* Get destination */ phys_copy(tab_phys + i*sizeof(tabent) + offsetof(struct asynmsg, dst), vir2phys(&tabent.dst), sizeof(tabent.dst)); if (tabent.dst != dst_e) { kprintf("try_one: wrong dst %d, looking for %d\n", tabent.dst, dst_e); continue; } #if 0 kprintf("try_one: entry[%d]: flags 0x%x dst %d\n", i, tabent.flags, tabent.dst); #endif /* Deliver message */ table_ptr= (asynmsg_t *)privp->s_asyntab; m_ptr= &table_ptr[i].msg; /* Note: pointer in the * caller's address space. */ CopyMess(src_ptr->p_nr, src_ptr, m_ptr, dst_ptr, dst_ptr->p_messbuf); tabent.result= OK; phys_copy(vir2phys(&tabent.result), tab_phys + i*sizeof(tabent) + offsetof(struct asynmsg, result), sizeof(tabent.result)); tabent.flags= flags | AMF_DONE; phys_copy(vir2phys(&tabent.flags), tab_phys + i*sizeof(tabent) + offsetof(struct asynmsg, flags), sizeof(tabent.flags)); if (flags & AMF_NOTIFY) { kprintf("try_one: should notify caller\n"); } return OK; } if (done) privp->s_asynsize= 0; return EAGAIN; } /*===========================================================================* * lock_notify * *===========================================================================*/ PUBLIC int lock_notify(src_e, dst_e) int src_e; /* (endpoint) sender of the notification */ int dst_e; /* (endpoint) who is to be notified */ { /* Safe gateway to mini_notify() for tasks and interrupt handlers. The sender * is explicitely given to prevent confusion where the call comes from. MINIX * kernel is not reentrant, which means to interrupts are disabled after * the first kernel entry (hardware interrupt, trap, or exception). Locking * is done by temporarily disabling interrupts. */ int result, src, dst; if(!isokendpt(src_e, &src) || !isokendpt(dst_e, &dst)) return EDEADSRCDST; /* Exception or interrupt occurred, thus already locked. */ if (k_reenter >= 0) { result = mini_notify(proc_addr(src), dst); } /* Call from task level, locking is required. */ else { lock(0, "notify"); result = mini_notify(proc_addr(src), dst); unlock(0); } return(result); } /*===========================================================================* * enqueue * *===========================================================================*/ PRIVATE void enqueue(rp) register struct proc *rp; /* this process is now runnable */ { /* Add 'rp' to one of the queues of runnable processes. This function is * responsible for inserting a process into one of the scheduling queues. * The mechanism is implemented here. The actual scheduling policy is * defined in sched() and pick_proc(). */ int q; /* scheduling queue to use */ int front; /* add to front or back */ #if DEBUG_SCHED_CHECK check_runqueues("enqueue1"); if (rp->p_ready) kprintf("enqueue() already ready process\n"); #endif /* Determine where to insert to process. */ sched(rp, &q, &front); /* Now add the process to the queue. */ if (rdy_head[q] == NIL_PROC) { /* add to empty queue */ rdy_head[q] = rdy_tail[q] = rp; /* create a new queue */ rp->p_nextready = NIL_PROC; /* mark new end */ } else if (front) { /* add to head of queue */ rp->p_nextready = rdy_head[q]; /* chain head of queue */ rdy_head[q] = rp; /* set new queue head */ } else { /* add to tail of queue */ rdy_tail[q]->p_nextready = rp; /* chain tail of queue */ rdy_tail[q] = rp; /* set new queue tail */ rp->p_nextready = NIL_PROC; /* mark new end */ } /* Now select the next process to run, if there isn't a current * process yet or current process isn't ready any more, or * it's PREEMPTIBLE. */ if(!proc_ptr || proc_ptr->p_rts_flags || (priv(proc_ptr)->s_flags & PREEMPTIBLE)) { pick_proc(); } #if DEBUG_SCHED_CHECK rp->p_ready = 1; check_runqueues("enqueue2"); #endif } /*===========================================================================* * dequeue * *===========================================================================*/ PRIVATE void dequeue(rp) register struct proc *rp; /* this process is no longer runnable */ { /* A process must be removed from the scheduling queues, for example, because * it has blocked. If the currently active process is removed, a new process * is picked to run by calling pick_proc(). */ register int q = rp->p_priority; /* queue to use */ register struct proc **xpp; /* iterate over queue */ register struct proc *prev_xp; /* Side-effect for kernel: check if the task's stack still is ok? */ if (iskernelp(rp)) { if (*priv(rp)->s_stack_guard != STACK_GUARD) panic("stack overrun by task", proc_nr(rp)); } #if DEBUG_SCHED_CHECK check_runqueues("dequeue1"); if (! rp->p_ready) kprintf("dequeue() already unready process\n"); #endif /* Now make sure that the process is not in its ready queue. Remove the * process if it is found. A process can be made unready even if it is not * running by being sent a signal that kills it. */ prev_xp = NIL_PROC; for (xpp = &rdy_head[q]; *xpp != NIL_PROC; xpp = &(*xpp)->p_nextready) { if (*xpp == rp) { /* found process to remove */ *xpp = (*xpp)->p_nextready; /* replace with next chain */ if (rp == rdy_tail[q]) /* queue tail removed */ rdy_tail[q] = prev_xp; /* set new tail */ if (rp == proc_ptr || rp == next_ptr) /* active process removed */ pick_proc(); /* pick new process to run */ break; } prev_xp = *xpp; /* save previous in chain */ } #if DEBUG_SCHED_CHECK rp->p_ready = 0; check_runqueues("dequeue2"); #endif } /*===========================================================================* * sched * *===========================================================================*/ PRIVATE void sched(rp, queue, front) register struct proc *rp; /* process to be scheduled */ int *queue; /* return: queue to use */ int *front; /* return: front or back */ { /* This function determines the scheduling policy. It is called whenever a * process must be added to one of the scheduling queues to decide where to * insert it. As a side-effect the process' priority may be updated. */ int time_left = (rp->p_ticks_left > 0); /* quantum fully consumed */ /* Check whether the process has time left. Otherwise give a new quantum * and lower the process' priority, unless the process already is in the * lowest queue. */ if (! time_left) { /* quantum consumed ? */ rp->p_ticks_left = rp->p_quantum_size; /* give new quantum */ if (rp->p_priority < (IDLE_Q-1)) { rp->p_priority += 1; /* lower priority */ } } /* If there is time left, the process is added to the front of its queue, * so that it can immediately run. The queue to use simply is always the * process' current priority. */ *queue = rp->p_priority; *front = time_left; } /*===========================================================================* * pick_proc * *===========================================================================*/ PRIVATE void pick_proc() { /* Decide who to run now. A new process is selected by setting 'next_ptr'. * When a billable process is selected, record it in 'bill_ptr', so that the * clock task can tell who to bill for system time. */ register struct proc *rp; /* process to run */ int q; /* iterate over queues */ /* Check each of the scheduling queues for ready processes. The number of * queues is defined in proc.h, and priorities are set in the task table. * The lowest queue contains IDLE, which is always ready. */ for (q=0; q < NR_SCHED_QUEUES; q++) { if ( (rp = rdy_head[q]) != NIL_PROC) { next_ptr = rp; /* run process 'rp' next */ if (priv(rp)->s_flags & BILLABLE) bill_ptr = rp; /* bill for system time */ return; } } panic("no ready process", NO_NUM); } /*===========================================================================* * balance_queues * *===========================================================================*/ #define Q_BALANCE_TICKS 100 PUBLIC void balance_queues(tp) timer_t *tp; /* watchdog timer pointer */ { /* Check entire process table and give all process a higher priority. This * effectively means giving a new quantum. If a process already is at its * maximum priority, its quantum will be renewed. */ static timer_t queue_timer; /* timer structure to use */ register struct proc* rp; /* process table pointer */ clock_t next_period; /* time of next period */ int ticks_added = 0; /* total time added */ for (rp=BEG_PROC_ADDR; rpp_priority > rp->p_max_priority) { /* update priority? */ if (rp->p_rts_flags == 0) dequeue(rp); /* take off queue */ ticks_added += rp->p_quantum_size; /* do accounting */ rp->p_priority -= 1; /* raise priority */ if (rp->p_rts_flags == 0) enqueue(rp); /* put on queue */ } else { ticks_added += rp->p_quantum_size - rp->p_ticks_left; rp->p_ticks_left = rp->p_quantum_size; /* give new quantum */ } unlock(5); } } #if DEBUG kprintf("ticks_added: %d\n", ticks_added); #endif /* Now schedule a new watchdog timer to balance the queues again. The * period depends on the total amount of quantum ticks added. */ next_period = MAX(Q_BALANCE_TICKS, ticks_added); /* calculate next */ set_timer(&queue_timer, get_uptime() + next_period, balance_queues); } /*===========================================================================* * lock_send * *===========================================================================*/ PUBLIC int lock_send(dst_e, m_ptr) int dst_e; /* to whom is message being sent? */ message *m_ptr; /* pointer to message buffer */ { /* Safe gateway to mini_send() for tasks. */ int result; lock(2, "send"); result = mini_send(proc_ptr, dst_e, m_ptr, NON_BLOCKING); unlock(2); return(result); } /*===========================================================================* * lock_enqueue * *===========================================================================*/ PUBLIC void lock_enqueue(rp) struct proc *rp; /* this process is now runnable */ { /* Safe gateway to enqueue() for tasks. */ lock(3, "enqueue"); enqueue(rp); unlock(3); } /*===========================================================================* * lock_dequeue * *===========================================================================*/ PUBLIC void lock_dequeue(rp) struct proc *rp; /* this process is no longer runnable */ { /* Safe gateway to dequeue() for tasks. */ if (k_reenter >= 0) { /* We're in an exception or interrupt, so don't lock (and ... * don't unlock). */ dequeue(rp); } else { lock(4, "dequeue"); dequeue(rp); unlock(4); } } /*===========================================================================* * isokendpt_f * *===========================================================================*/ #if DEBUG_ENABLE_IPC_WARNINGS PUBLIC int isokendpt_f(file, line, e, p, fatalflag) char *file; int line; #else PUBLIC int isokendpt_f(e, p, fatalflag) #endif endpoint_t e; int *p, fatalflag; { int ok = 0; /* Convert an endpoint number into a process number. * Return nonzero if the process is alive with the corresponding * generation number, zero otherwise. * * This function is called with file and line number by the * isokendpt_d macro if DEBUG_ENABLE_IPC_WARNINGS is defined, * otherwise without. This allows us to print the where the * conversion was attempted, making the errors verbose without * adding code for that at every call. * * If fatalflag is nonzero, we must panic if the conversion doesn't * succeed. */ *p = _ENDPOINT_P(e); if(!isokprocn(*p)) { #if DEBUG_ENABLE_IPC_WARNINGS kprintf("kernel:%s:%d: bad endpoint %d: proc %d out of range\n", file, line, e, *p); #endif } else if(isemptyn(*p)) { #if DEBUG_ENABLE_IPC_WARNINGS kprintf("kernel:%s:%d: bad endpoint %d: proc %d empty\n", file, line, e, *p); #endif } else if(proc_addr(*p)->p_endpoint != e) { #if DEBUG_ENABLE_IPC_WARNINGS kprintf("kernel:%s:%d: bad endpoint %d: proc %d has ept %d (generation %d vs. %d)\n", file, line, e, *p, proc_addr(*p)->p_endpoint, _ENDPOINT_G(e), _ENDPOINT_G(proc_addr(*p)->p_endpoint)); #endif } else ok = 1; if(!ok && fatalflag) { panic("invalid endpoint ", e); } return ok; }