Re: [PATCH 14/14] FRV: Better mmap support in uClinux

[Christoph Hellwig <hch@infradead.org>]

> diff -uNr /warthog/kernels/linux-2.6.10-rc1-bk10/fs/proc/base.c linux-2.6.10-rc1-bk10-frv/fs/proc/base.c
> --- /warthog/kernels/linux-2.6.10-rc1-bk10/fs/proc/base.c	2004-10-27 17:32:31.000000000 +0100
> +++ linux-2.6.10-rc1-bk10-frv/fs/proc/base.c	2004-11-01 11:47:04.870656963 +0000
> @@ -220,6 +220,9 @@
>  
>  static int proc_exe_link(struct inode *inode, struct dentry **dentry, struct vfsmount **mnt)
>  {
> +#ifndef CONFIG_MMU
> +	struct mm_tblock_struct *tblock;
> +#endif
>  	struct vm_area_struct * vma;
>  	int result = -ENOENT;
>  	struct task_struct *task = proc_task(inode);
> @@ -228,17 +231,32 @@
>  	if (!mm)
>  		goto out;
>  	down_read(&mm->mmap_sem);
> +
> +#ifdef CONFIG_MMU
>  	vma = mm->mmap;
>  	while (vma) {
> -		if ((vma->vm_flags & VM_EXECUTABLE) && 
> -		    vma->vm_file) {
> -			*mnt = mntget(vma->vm_file->f_vfsmnt);
> -			*dentry = dget(vma->vm_file->f_dentry);
> -			result = 0;
> +		if ((vma->vm_flags & VM_EXECUTABLE) && vma->vm_file)
>  			break;
> -		}
>  		vma = vma->vm_next;
>  	}
> +#else
> +	tblock = mm->context.tblock;
> +	vma = NULL;
> +	while (tblock) {
> +		if ((tblock->vma->vm_flags & VM_EXECUTABLE) && tblock->vma->vm_file) {
> +			vma = tblock->vma;
> +			break;
> +		}
> +		tblock = tblock->next;
> +	}
> +#endif
> +
> +	if (vma) {
> +		*mnt = mntget(vma->vm_file->f_vfsmnt);
> +		*dentry = dget(vma->vm_file->f_dentry);
> +		result = 0;
> +	}
> +
>  	up_read(&mm->mmap_sem);
>  	mmput(mm);

please split this up into a mmu and a no-mmu function, in a mmu and nommu
file respectively.

>  #include <linux/pagemap.h>
>  #include <linux/slab.h>
>  #include <linux/vmalloc.h>
> +#include <linux/ptrace.h>
>  #include <linux/blkdev.h>
>  #include <linux/backing-dev.h>
>  #include <linux/syscalls.h>
> @@ -38,6 +40,10 @@
>  EXPORT_SYMBOL(sysctl_max_map_count);
>  EXPORT_SYMBOL(mem_map);
>  
> +/* list of shareable VMAs */
> +LIST_HEAD(shareable_vma_list);
> +DECLARE_RWSEM(shareable_vma_sem);

the should both be static

> +	if (flags & MAP_FIXED || addr) {
> +//		printk("can't do fixed-address/overlay mmap of RAM\n");

please avoid C++-style comments in core kernel code.

> diff -uNr /warthog/kernels/linux-2.6.10-rc1-bk10/mm/tiny-shmem.c linux-2.6.10-rc1-bk10-frv/mm/tiny-shmem.c
> --- /warthog/kernels/linux-2.6.10-rc1-bk10/mm/tiny-shmem.c	2004-10-27 17:32:38.000000000 +0100
> +++ linux-2.6.10-rc1-bk10-frv/mm/tiny-shmem.c	2004-11-01 14:24:49.419177784 +0000
> @@ -112,7 +112,9 @@
>  	if (vma->vm_file)
>  		fput(vma->vm_file);
>  	vma->vm_file = file;
> +#ifdef CONFIG_MMU
>  	vma->vm_ops = &generic_file_vm_ops;
> +#endif

please find a nice way to abstract this out without the ifdefs here.