procfs: if memory_range_lock fails, process later

Change-Id: I3c5f24548455a63d8d5a4482f5081347f631885a
Refs: #452

kernel/host.c

@@ -601,6 +601,20 @@ extern unsigned long do_kill(struct thread *, int, int, int, struct siginfo *, i
 extern void terminate_host(int pid);
 extern void debug_log(long);
 
+void send_procfs_answer(struct ikc_scd_packet *packet, int err)
+{
+	struct ikc_scd_packet pckt;
+	struct ihk_ikc_channel_desc *resp_channel = cpu_local_var(ikc2linux);
+
+	pckt.msg = SCD_MSG_PROCFS_ANSWER;
+	pckt.ref = packet->ref;
+	pckt.arg = packet->arg;
+	pckt.err = err;
+	pckt.reply = packet->reply;
+	pckt.pid = packet->pid;
+	syscall_channel_send(resp_channel, &pckt);
+}
+
 static int syscall_packet_handler(struct ihk_ikc_channel_desc *c,
                                   void *__packet, void *ihk_os)
 {
@@ -745,13 +759,7 @@ out_remote_pf:
 
 	case SCD_MSG_PROCFS_REQUEST:
 	case SCD_MSG_PROCFS_RELEASE:
-		pckt.msg = SCD_MSG_PROCFS_ANSWER;
-		pckt.ref = packet->ref;
-		pckt.arg = packet->arg;
-		pckt.err = process_procfs_request(packet);
-		pckt.reply = packet->reply;
-		pckt.pid = packet->pid;
-		syscall_channel_send(resp_channel, &pckt);
+		process_procfs_request(packet);
 		ret = 0;
 		break;
 

kernel/include/syscall.h

@@ -412,6 +412,7 @@ struct procfs_file {
 };
 
 int process_procfs_request(struct ikc_scd_packet *rpacket);
+void send_procfs_answer(struct ikc_scd_packet *packet, int err);
 
 #define RUSAGE_SELF 0
 #define RUSAGE_CHILDREN -1

kernel/procfs.c

@@ -38,6 +38,7 @@
 extern int snprintf(char *buf, size_t size, const char *fmt, ...);
 extern int sscanf(const char * buf, const char * fmt, ...);
 extern int scnprintf(char * buf, size_t size, const char *fmt, ...);
+static int do_procfs_backlog(void *arg);
 
 struct mckernel_procfs_buffer {
 	unsigned long next_pa;
@@ -148,12 +149,28 @@ procfs_delete_thread(struct thread *thread)
 	procfs_thread_ctl(thread, SCD_MSG_PROCFS_TID_DELETE);
 }
 
+static int procfs_backlog(struct process_vm *vm, struct ikc_scd_packet *rpacket)
+{
+	void *arg;
+	int err;
+
+	if (!(arg = kmalloc(sizeof(struct ikc_scd_packet), IHK_MC_AP_NOWAIT))) {
+		return -ENOMEM;
+	}
+	memcpy(arg, rpacket, sizeof(struct ikc_scd_packet));
+	if ((err = add_backlog(do_procfs_backlog, arg))) {
+		kfree(arg);
+		return err;
+	}
+	return 0;
+}
+
 /**
  * \brief The callback function for mckernel procfs files.
  *
  * \param rarg returned argument
  */
-int process_procfs_request(struct ikc_scd_packet *rpacket)
+static int _process_procfs_request(struct ikc_scd_packet *rpacket, int *result)
 {
 	unsigned long rarg = rpacket->arg;
 	unsigned long parg, pbuf;
@@ -419,7 +436,17 @@ int process_procfs_request(struct ikc_scd_packet *rpacket)
 	if (strcmp(p, "maps") == 0) {
 		struct vm_range *range;
 
-		ihk_mc_spinlock_lock_noirq(&vm->memory_range_lock);
+		if (!ihk_mc_spinlock_trylock_noirq(&vm->memory_range_lock)) {
+			if (!result) {
+				if ((err = procfs_backlog(vm, rpacket))) {
+					goto err;
+				}
+			}
+			else {
+				*result = -EAGAIN;
+			}
+			goto out;
+		}
 
 		range = lookup_process_memory_range(vm, 0, -1);
 		while (range) {
@@ -455,14 +482,15 @@ int process_procfs_request(struct ikc_scd_packet *rpacket)
 
 			if (ans < 0 || ans > count ||
 			    buf_add(&buf_top, &buf_cur, buf, ans) < 0) {
-				ihk_mc_spinlock_unlock_noirq(&vm->memory_range_lock);
+				ihk_mc_spinlock_unlock_noirq(
+							&vm->memory_range_lock);
 				goto err;
 			}
 			range = next_process_memory_range(vm, range);
 		}
-		
+
 		ihk_mc_spinlock_unlock_noirq(&vm->memory_range_lock);
-		
+
 		ans = 0;
 		goto end;
 	}
@@ -483,8 +511,18 @@ int process_procfs_request(struct ikc_scd_packet *rpacket)
 
 		start = (offset / sizeof(uint64_t)) << PAGE_SHIFT;
 		end = start + ((count / sizeof(uint64_t)) << PAGE_SHIFT);
-		
-		ihk_mc_spinlock_lock_noirq(&vm->memory_range_lock);
+
+		if (!ihk_mc_spinlock_trylock_noirq(&vm->memory_range_lock)) {
+			if (!result) {
+				if ((err = procfs_backlog(vm, rpacket))) {
+					goto err;
+				}
+			}
+			else {
+				*result = -EAGAIN;
+			}
+			goto out;
+		}
 
 		while (start < end) {
 			*_buf = ihk_mc_pt_virt_to_pagemap(proc->vm->address_space->page_table, start);
@@ -495,7 +533,7 @@ int process_procfs_request(struct ikc_scd_packet *rpacket)
 		}
 
 		ihk_mc_spinlock_unlock_noirq(&vm->memory_range_lock);
-		
+
 		dprintf("/proc/pagemap: 0x%lx - 0x%lx, count: %d\n", 
 			start, end, count);
 		
@@ -526,14 +564,24 @@ int process_procfs_request(struct ikc_scd_packet *rpacket)
 			goto err;
 		}
 
-		ihk_mc_spinlock_lock_noirq(&proc->vm->memory_range_lock);
+		if (!ihk_mc_spinlock_trylock_noirq(&vm->memory_range_lock)) {
+			if (!result) {
+				if ((err = procfs_backlog(vm, rpacket))) {
+					goto err;
+				}
+			}
+			else {
+				*result = -EAGAIN;
+			}
+			goto out;
+		}
 		range = lookup_process_memory_range(vm, 0, -1);
 		while (range) {
 			if(range->flag & VR_LOCKED)
 				lockedsize += range->end - range->start;
 			range = next_process_memory_range(vm, range);
 		}
-		ihk_mc_spinlock_unlock_noirq(&proc->vm->memory_range_lock);
+		ihk_mc_spinlock_unlock_noirq(&vm->memory_range_lock);
 
 		cpu_bitmask = &bitmasks[bitmasks_offset];
 		bitmasks_offset += bitmap_scnprintf(cpu_bitmask,
@@ -786,6 +834,9 @@ end:
 	if (r->pbuf == PA_NULL && buf_top)
 		r->pbuf = virt_to_phys(buf_top);
 err:
+	send_procfs_answer(rpacket, err);
+
+out:
 	if (vbuf) {
 		ihk_mc_unmap_virtual(vbuf, npages);
 		ihk_mc_unmap_memory(NULL, pbuf, r->count);
@@ -807,3 +858,20 @@ err:
 
 	return err;
 }
+
+int process_procfs_request(struct ikc_scd_packet *rpacket)
+{
+	return _process_procfs_request(rpacket, NULL);
+}
+
+static int do_procfs_backlog(void *arg)
+{
+	struct ikc_scd_packet *rpacket = arg;
+	int result = 0;
+
+	_process_procfs_request(rpacket, &result);
+	if (!result) {
+		kfree(arg);
+	}
+	return result;
+}