Add linux 5.6 support to Parallels Desktop 15 Guest Tools. Based on a discussion here: https://gist.github.com/mag911/1a5583a766467d6023584d738cee0d98

parallels-15-guest-tools-patch-for-linux-5-6.patch

For ubuntu 20.04 / linux 5.6 support, apply this patch to the root of the
prl_mod.tar.gz archive found in the ISO of the Parallels Desktop 15 Guest
Tools. This is a hack that contains a small memory leak. I have little
experience hacking on the linux kernel, use at your own risk.

---
 .../Guest/Linux/prl_fs/prlfs_compat.h           | 17 ++++++++++++++++-
 .../Linux/prl_freeze/prlfs_freeze_compat.h      | 16 +++++++++++++++-
 prl_tg/Toolgate/Guest/Linux/prl_tg/prltg.c      | 16 +++++++++++++++-
 prl_tg/Toolgate/Guest/Linux/prl_tg/prltg_call.c |  4 ++--
 4 files changed, 48 insertions(+), 5 deletions(-)

diff --git a/prl_fs/SharedFolders/Guest/Linux/prl_fs/prlfs_compat.h b/prl_fs/SharedFolders/Guest/Linux/prl_fs/prlfs_compat.h
index 5d20399..edca98a 100644
--- a/prl_fs/SharedFolders/Guest/Linux/prl_fs/prlfs_compat.h
+++ b/prl_fs/SharedFolders/Guest/Linux/prl_fs/prlfs_compat.h
@@ -18,8 +18,23 @@ prlfs_proc_create(char *name, umode_t mode, struct proc_dir_entry *parent,
 	if (p)
 		p->proc_fops = fops;
 	return p;
-#else
+#elif LINUX_VERSION_CODE < KERNEL_VERSION(5,6,0)
 	return proc_create(name, mode, parent, fops);
+#else
+	// fun little memory leak
+	struct proc_ops *converted_proc_ops;
+	converted_proc_ops = (struct proc_ops *) kmalloc(sizeof(struct proc_ops), GFP_KERNEL);
+	*converted_proc_ops = ( struct proc_ops ){
+		.proc_open = fops->open,
+		.proc_write = fops->write,
+		.proc_lseek = fops->llseek,
+		.proc_poll = fops->poll,
+		.proc_ioctl = fops->unlocked_ioctl,
+		.proc_mmap = fops->mmap,
+		.proc_release = fops->release,
+		.proc_get_unmapped_area = fops->get_unmapped_area,
+	};
+	return proc_create(name, mode, parent, converted_proc_ops);
 #endif
 }
 
diff --git a/prl_fs_freeze/Snapshot/Guest/Linux/prl_freeze/prlfs_freeze_compat.h b/prl_fs_freeze/Snapshot/Guest/Linux/prl_freeze/prlfs_freeze_compat.h
index 2378ebf..f0eabb6 100644
--- a/prl_fs_freeze/Snapshot/Guest/Linux/prl_freeze/prlfs_freeze_compat.h
+++ b/prl_fs_freeze/Snapshot/Guest/Linux/prl_freeze/prlfs_freeze_compat.h
@@ -17,8 +17,22 @@ prlfs_freeze_proc_create(char *name, umode_t mode,
 	if (p)
 		p->proc_fops = fops;
 	return p;
-#else
+#elif LINUX_VERSION_CODE < KERNEL_VERSION(5,6,0)
 	return proc_create(name, mode, parent, fops);
+#else
+	// fun little memory leak
+	struct proc_ops *converted_proc_ops = kmalloc(sizeof(struct proc_ops), GFP_KERNEL);
+	*converted_proc_ops = ( struct proc_ops ){
+		.proc_open = fops->open,
+		.proc_write = fops->write,
+		.proc_lseek = fops->llseek,
+		.proc_poll = fops->poll,
+		.proc_ioctl = fops->unlocked_ioctl,
+		.proc_mmap = fops->mmap,
+		.proc_release = fops->release,
+		.proc_get_unmapped_area = fops->get_unmapped_area,
+	};
+	return proc_create(name, mode, parent, converted_proc_ops);
 #endif
 }
 
diff --git a/prl_tg/Toolgate/Guest/Linux/prl_tg/prltg.c b/prl_tg/Toolgate/Guest/Linux/prl_tg/prltg.c
index 6213542..42b33e6 100644
--- a/prl_tg/Toolgate/Guest/Linux/prl_tg/prltg.c
+++ b/prl_tg/Toolgate/Guest/Linux/prl_tg/prltg.c
@@ -401,8 +401,22 @@ prltg_proc_create_data(char *name, umode_t mode, struct proc_dir_entry *parent,
 		p->data = data;
 	}
 	return p;
-#else
+#elif LINUX_VERSION_CODE < KERNEL_VERSION(5,6,0)
 	return proc_create_data(name, mode, parent, fops, data);
+#else
+	// fun little memory leak
+	struct proc_ops *converted_proc_ops = kmalloc(sizeof(struct proc_ops), GFP_KERNEL);
+	*converted_proc_ops = ( struct proc_ops ){
+		.proc_open = fops->open,
+		.proc_write = fops->write,
+		.proc_lseek = fops->llseek,
+		.proc_poll = fops->poll,
+		.proc_ioctl = fops->unlocked_ioctl,
+		.proc_mmap = fops->mmap,
+		.proc_release = fops->release,
+		.proc_get_unmapped_area = fops->get_unmapped_area,
+	};
+	return proc_create_data(name, mode, parent, converted_proc_ops, data);
 #endif
 }
 
diff --git a/prl_tg/Toolgate/Guest/Linux/prl_tg/prltg_call.c b/prl_tg/Toolgate/Guest/Linux/prl_tg/prltg_call.c
index 269c345..1c6305c 100644
--- a/prl_tg/Toolgate/Guest/Linux/prl_tg/prltg_call.c
+++ b/prl_tg/Toolgate/Guest/Linux/prl_tg/prltg_call.c
@@ -106,13 +106,13 @@ static TG_PAGED_BUFFER *tg_req_map_user_pages(struct TG_PENDING_REQUEST *req,
 	uple->writable = sbuf->Writable;
 	uple->count = npages;
 
-	down_read(&current->mm->mmap_sem);
+	mmap_read_lock(current->mm);
 	/* lock userspace pages */
 	got = prl_get_user_pages(
 				 sbuf->u.Va, npages,
 				 sbuf->Writable,
 				 uple->p, NULL);
-	up_read(&current->mm->mmap_sem);
+	mmap_read_unlock(current->mm);
 
 	if (got < npages) {
 		DPRINTK("[2] %d < %d	\n", got, npages);
-- 
2.31.1