From: Thomas Veerman <thomas@minix3.org>
Date: Thu, 27 Oct 2011 15:26:08 +0000 (+0000)
Subject: Reenable backcall detection
X-Git-Tag: v3.2.0~284
X-Git-Url: http://zhaoyanbai.com/repos/%22http:/www.isc.org/icons/Bv9ARM.ch10.html?a=commitdiff_plain;h=febb4403ff9767d607d5db9e8fd8b7dc8e6ce2bf;p=minix.git

Reenable backcall detection
---

diff --git a/servers/avfs/comm.c b/servers/avfs/comm.c
index 8546622ac..b11b06e05 100644
--- a/servers/avfs/comm.c
+++ b/servers/avfs/comm.c
@@ -62,7 +62,7 @@ PUBLIC void fs_sendmore(struct vmnt *vmp)
 	return;
   if (vmp->m_comm.c_cur_reqs >= vmp->m_comm.c_max_reqs)/*No room to send more*/
 	return;
-  if (vmp->m_flags & VMNT_BACKCALL)	/* Hold off for now */
+  if (vmp->m_flags & VMNT_CALLBACK)	/* Hold off for now */
 	return;
 
   vmp->m_comm.c_req_queue = worker->w_next; /* Remove head */
@@ -88,7 +88,7 @@ PUBLIC int fs_sendrec(endpoint_t fs_e, message *reqmp)
 	fp->fp_sendrec = reqmp;	/* Where to store request and reply */
 
 	/* Find out whether we can send right away or have to enqueue */
-	if (	!(vmp->m_flags & VMNT_BACKCALL) &&
+	if (	!(vmp->m_flags & VMNT_CALLBACK) &&
 		vmp->m_comm.c_cur_reqs < vmp->m_comm.c_max_reqs) {
 		/* There's still room to send more and no proc is queued */
 		r = sendmsg(vmp, fp);
diff --git a/servers/avfs/dmap.c b/servers/avfs/dmap.c
index d73aa1fac..687f0c2aa 100644
--- a/servers/avfs/dmap.c
+++ b/servers/avfs/dmap.c
@@ -96,7 +96,7 @@ int flags;			/* device flags */
   dp = &dmap[major];
 
   /* Check if we're supposed to unmap it. */
- if(proc_nr_e == NONE) {
+ if (proc_nr_e == NONE) {
 	dp->dmap_opcl = no_dev;
 	dp->dmap_io = no_dev_io;
 	dp->dmap_driver = NONE;
@@ -106,8 +106,13 @@ int flags;			/* device flags */
 
   /* Check process number of new driver if it was alive before mapping */
   if (! (flags & DRV_FORCED)) {
+	struct fproc *rfp;
+
 	if (isokendpt(proc_nr_e, &slot) != OK)
 		return(EINVAL);
+
+	rfp = &fproc[slot];
+	rfp->fp_flags |= FP_SYS_PROC;	/* Process is a driver */
   }
 
   if (label != NULL) {
diff --git a/servers/avfs/fproc.h b/servers/avfs/fproc.h
index 465c8ed64..43f2012d2 100644
--- a/servers/avfs/fproc.h
+++ b/servers/avfs/fproc.h
@@ -58,11 +58,12 @@ EXTERN struct fproc {
 #define FP_SUSP_REOPEN	01	/* Process is suspended until the reopens are
 				 * completed (after the restart of a driver).
 				 */
-#define FP_REVIVED	02	/* Indicates process is being revived */
-#define FP_SESLDR	04	/* Set if process is session leader */
-#define FP_PENDING	010	/* Set if process has pending work */
-#define FP_EXITING	020	/* Set if process is exiting */
-#define FP_PM_PENDING	040	/* Set if process has pending PM request */
+#define FP_REVIVED	 0002	/* Indicates process is being revived */
+#define FP_SESLDR	 0004	/* Set if process is session leader */
+#define FP_PENDING	 0010	/* Set if process has pending work */
+#define FP_EXITING	 0020	/* Set if process is exiting */
+#define FP_PM_PENDING	 0040	/* Set if process has pending PM request */
+#define FP_SYS_PROC	 0100	/* Set if process is a driver or FS */
 
 /* Field values. */
 #define NOT_REVIVING       0xC0FFEEE	/* process is not being revived */
diff --git a/servers/avfs/main.c b/servers/avfs/main.c
index 135ab38d8..e07f66ef6 100644
--- a/servers/avfs/main.c
+++ b/servers/avfs/main.c
@@ -77,7 +77,7 @@ PUBLIC int main(void)
   /* SEF local startup. */
   sef_local_startup();
 
-  printf("Started AVFS\n");
+  printf("Started AVFS: %d worker thread(s)\n", NR_WTHREADS);
   verbose = 0;
 
   /* This is the main loop that gets work, processes it, and sends replies. */
@@ -140,12 +140,16 @@ PRIVATE void handle_work(void *(*func)(void *arg))
 {
 /* Handle asynchronous device replies and new system calls. If the originating
  * endpoint is an FS endpoint, take extra care not to get in deadlock. */
- struct vmnt *vmp;
+  struct vmnt *vmp = NULL;
 
   if ((vmp = find_vmnt(who_e)) != NULL) {
-	/* A back call or dev result from an FS endpoint */
+	/* A call back or dev result from an FS endpoint */
 
-	/* When an FS point has to make a callback in order to mount, force
+	/* Set call back flag. We assume that an FS does only one call back
+	 * at a time */
+	vmp->m_flags |= VMNT_CALLBACK;
+
+	/* When an FS point has to make a call back in order to mount, force
 	 * its device to a "none device" so block reads/writes will be handled
 	 * by ROOT_FS_E.
 	 */
@@ -157,6 +161,7 @@ PRIVATE void handle_work(void *(*func)(void *arg))
 		if (deadlock_resolving) {
 			/* Already trying to resolve a deadlock, can't
 			 * handle more, sorry */
+			vmp->m_flags &= ~VMNT_CALLBACK;
 			reply(who_e, EAGAIN);
 			return;
 		}
@@ -208,6 +213,13 @@ PRIVATE void *do_async_dev_result(void *arg)
 		deadlock_resolving = 0;
   }
 
+  if (fp != NULL && (fp->fp_flags & FP_SYS_PROC)) {
+	struct vmnt *vmp;
+
+	if ((vmp = find_vmnt(fp->fp_endpoint)) != NULL)
+		vmp->m_flags &= ~VMNT_CALLBACK;
+  }
+
   thread_cleanup(NULL);
   return(NULL);
 }
@@ -425,6 +437,14 @@ PRIVATE void *do_work(void *arg)
 
   /* Copy the results back to the user and send reply. */
   if (error != SUSPEND) {
+
+	if ((fp->fp_flags & FP_SYS_PROC)) {
+		struct vmnt *vmp;
+
+		if ((vmp = find_vmnt(fp->fp_endpoint)) != NULL)
+			vmp->m_flags &= ~VMNT_CALLBACK;
+	}
+
 	if (deadlock_resolving) {
 		if (fp->fp_wtid == dl_worker.w_tid)
 			deadlock_resolving = 0;
diff --git a/servers/avfs/mount.c b/servers/avfs/mount.c
index 656995732..362a2d4ec 100644
--- a/servers/avfs/mount.c
+++ b/servers/avfs/mount.c
@@ -167,8 +167,8 @@ int rdonly,
 char mount_label[LABEL_MAX] )
 {
   int rdir, mdir;               /* TRUE iff {root|mount} file is dir */
-  int i, r = OK, found, isroot, mount_root, con_reqs;
-  struct fproc *tfp;
+  int i, r = OK, found, isroot, mount_root, con_reqs, slot;
+  struct fproc *tfp, *rfp;
   struct dmap *dp;
   struct vnode *root_node, *vp = NULL;
   struct vmnt *new_vmp, *parent_vmp;
@@ -249,6 +249,12 @@ char mount_label[LABEL_MAX] )
 
   lock_vnode(root_node, VNODE_OPCL);
 
+  /* Record process as a system process */
+  if (isokendpt(fs_e, &slot) != OK)
+	return(EINVAL);
+  rfp = &fproc[slot];
+  rfp->fp_flags |= FP_SYS_PROC;	/* Process is an FS */
+
   /* Store some essential vmnt data first */
   new_vmp->m_fs_e = fs_e;
   new_vmp->m_dev = dev;
diff --git a/servers/avfs/vmnt.h b/servers/avfs/vmnt.h
index 510502c01..14d00b3ab 100644
--- a/servers/avfs/vmnt.h
+++ b/servers/avfs/vmnt.h
@@ -14,7 +14,7 @@ EXTERN struct vmnt {
 
 /* vmnt flags */
 #define VMNT_READONLY		01	/* Device mounted readonly */
-#define VMNT_BACKCALL		02	/* FS did back call */
+#define VMNT_CALLBACK		02	/* FS did back call */
 #define VMNT_MOUNTING		04	/* Device is being mounted */
 #define VMNT_FORCEROOTBSF	010	/* Force usage of none-device */