svn commit: r185765 - in head/sys: compat/linprocfs fs/procfs

Kostik Belousov kostikbel at gmail.com
Mon Dec 8 05:01:51 PST 2008


On Mon, Dec 08, 2008 at 12:34:52PM +0000, Konstantin Belousov wrote:
> Author: kib
> Date: Mon Dec  8 12:34:52 2008
> New Revision: 185765
> URL: http://svn.freebsd.org/changeset/base/185765
> 
> Log:
>   Change the linprocfs <pid>/maps and procfs <pid>/map handlers to use
>   sbuf instead of doing uiomove. This allows for reads from non-zero
>   offsets to work.
>   
>   Patch is forward-ported des@' one, and was adopted to current code
>   by dchagin@ and me.
>   
>   Reviewed by:	des (linprocfs part)
>   PR:	kern/101453
>   MFC after:	1 week
> 
> Modified:
>   head/sys/compat/linprocfs/linprocfs.c
>   head/sys/fs/procfs/procfs_map.c

Thanks for Roman Divacky for pointing this out, commit message is wrong.
I specified wrong log file to the svn ci -F switch.
The right commit message is below.

In procfs map handler, and in linprocfs maps handler, do not call
vn_fullpath() while having vm map locked. This is done in anticipation
of the vop_vptocnp commit, that would make vn_fullpath sometime
acquire vnode lock.

Also, in linprocfs, maps handler already acquires vnode lock.

No objections from:	des
MFC after:	2 week

> 
> Modified: head/sys/compat/linprocfs/linprocfs.c
> ==============================================================================
> --- head/sys/compat/linprocfs/linprocfs.c	Mon Dec  8 12:29:30 2008	(r185764)
> +++ head/sys/compat/linprocfs/linprocfs.c	Mon Dec  8 12:34:52 2008	(r185765)
> @@ -876,10 +876,12 @@ static int
>  linprocfs_doprocmaps(PFS_FILL_ARGS)
>  {
>  	vm_map_t map = &p->p_vmspace->vm_map;
> -	vm_map_entry_t entry;
> +	vm_map_entry_t entry, tmp_entry;
>  	vm_object_t obj, tobj, lobj;
> -	vm_offset_t saved_end;
> +	vm_offset_t e_start, e_end;
>  	vm_ooffset_t off = 0;
> +	vm_prot_t e_prot;
> +	unsigned int last_timestamp;
>  	char *name = "", *freename = NULL;
>  	ino_t ino;
>  	int ref_count, shadow_count, flags;
> @@ -905,7 +907,9 @@ linprocfs_doprocmaps(PFS_FILL_ARGS)
>  		freename = NULL;
>  		if (entry->eflags & MAP_ENTRY_IS_SUB_MAP)
>  			continue;
> -		saved_end = entry->end;
> +		e_prot = entry->protection;
> +		e_start = entry->start;
> +		e_end = entry->end;
>  		obj = entry->object.vm_object;
>  		for (lobj = tobj = obj; tobj; tobj = tobj->backing_object) {
>  			VM_OBJECT_LOCK(tobj);
> @@ -913,6 +917,8 @@ linprocfs_doprocmaps(PFS_FILL_ARGS)
>  				VM_OBJECT_UNLOCK(lobj);
>  			lobj = tobj;
>  		}
> +		last_timestamp = map->timestamp;
> +		vm_map_unlock_read(map);
>  		ino = 0;
>  		if (lobj) {
>  			off = IDX_TO_OFF(lobj->size);
> @@ -950,10 +956,10 @@ linprocfs_doprocmaps(PFS_FILL_ARGS)
>  		 */
>  		error = sbuf_printf(sb,
>  		    "%08lx-%08lx %s%s%s%s %08lx %02x:%02x %lu%s%s\n",
> -		    (u_long)entry->start, (u_long)entry->end,
> -		    (entry->protection & VM_PROT_READ)?"r":"-",
> -		    (entry->protection & VM_PROT_WRITE)?"w":"-",
> -		    (entry->protection & VM_PROT_EXECUTE)?"x":"-",
> +		    (u_long)e_start, (u_long)e_end,
> +		    (e_prot & VM_PROT_READ)?"r":"-",
> +		    (e_prot & VM_PROT_WRITE)?"w":"-",
> +		    (e_prot & VM_PROT_EXECUTE)?"x":"-",
>  		    "p",
>  		    (u_long)off,
>  		    0,
> @@ -968,6 +974,16 @@ linprocfs_doprocmaps(PFS_FILL_ARGS)
>  			error = 0;
>  			break;
>  		}
> +		vm_map_lock_read(map);
> +		if (last_timestamp + 1 != map->timestamp) {
> +			/*
> +			 * Look again for the entry because the map was
> +			 * modified while it was unlocked.  Specifically,
> +			 * the entry may have been clipped, merged, or deleted.
> +			 */
> +			vm_map_lookup_entry(map, e_end - 1, &tmp_entry);
> +			entry = tmp_entry;
> +		}
>  	}
>  	vm_map_unlock_read(map);
>  
> 
> Modified: head/sys/fs/procfs/procfs_map.c
> ==============================================================================
> --- head/sys/fs/procfs/procfs_map.c	Mon Dec  8 12:29:30 2008	(r185764)
> +++ head/sys/fs/procfs/procfs_map.c	Mon Dec  8 12:34:52 2008	(r185765)
> @@ -84,9 +84,10 @@ procfs_doprocmap(PFS_FILL_ARGS)
>  {
>  	int error, vfslocked;
>  	vm_map_t map = &p->p_vmspace->vm_map;
> -	vm_map_entry_t entry;
> +	vm_map_entry_t entry, tmp_entry;
>  	struct vnode *vp;
>  	char *fullpath, *freepath;
> +	unsigned int last_timestamp;
>  #ifdef COMPAT_IA32
>  	int wrap32 = 0;
>  #endif
> @@ -113,13 +114,19 @@ procfs_doprocmap(PFS_FILL_ARGS)
>  	     entry = entry->next) {
>  		vm_object_t obj, tobj, lobj;
>  		int ref_count, shadow_count, flags;
> -		vm_offset_t addr;
> +		vm_offset_t e_start, e_end, addr;
>  		int resident, privateresident;
>  		char *type;
> +		vm_eflags_t e_eflags;
> +		vm_prot_t e_prot;
>  
>  		if (entry->eflags & MAP_ENTRY_IS_SUB_MAP)
>  			continue;
>  
> +		e_eflags = entry->eflags;
> +		e_prot = entry->protection;
> +		e_start = entry->start;
> +		e_end = entry->end;
>  		privateresident = 0;
>  		obj = entry->object.vm_object;
>  		if (obj != NULL) {
> @@ -143,11 +150,13 @@ procfs_doprocmap(PFS_FILL_ARGS)
>  				VM_OBJECT_UNLOCK(lobj);
>  			lobj = tobj;
>  		}
> +		last_timestamp = map->timestamp;
> +		vm_map_unlock_read(map);
>  
>  		freepath = NULL;
>  		fullpath = "-";
>  		if (lobj) {
> -			switch(lobj->type) {
> +			switch (lobj->type) {
>  			default:
>  			case OBJT_DEFAULT:
>  				type = "default";
> @@ -193,19 +202,19 @@ procfs_doprocmap(PFS_FILL_ARGS)
>  		 */
>  		error = sbuf_printf(sb,
>  		    "0x%lx 0x%lx %d %d %p %s%s%s %d %d 0x%x %s %s %s %s\n",
> -			(u_long)entry->start, (u_long)entry->end,
> +			(u_long)e_start, (u_long)e_end,
>  			resident, privateresident,
>  #ifdef COMPAT_IA32
>  			wrap32 ? NULL : obj,	/* Hide 64 bit value */
>  #else
>  			obj,
>  #endif
> -			(entry->protection & VM_PROT_READ)?"r":"-",
> -			(entry->protection & VM_PROT_WRITE)?"w":"-",
> -			(entry->protection & VM_PROT_EXECUTE)?"x":"-",
> +			(e_prot & VM_PROT_READ)?"r":"-",
> +			(e_prot & VM_PROT_WRITE)?"w":"-",
> +			(e_prot & VM_PROT_EXECUTE)?"x":"-",
>  			ref_count, shadow_count, flags,
> -			(entry->eflags & MAP_ENTRY_COW)?"COW":"NCOW",
> -			(entry->eflags & MAP_ENTRY_NEEDS_COPY)?"NC":"NNC",
> +			(e_eflags & MAP_ENTRY_COW)?"COW":"NCOW",
> +			(e_eflags & MAP_ENTRY_NEEDS_COPY)?"NC":"NNC",
>  			type, fullpath);
>  
>  		if (freepath != NULL)
> @@ -215,6 +224,16 @@ procfs_doprocmap(PFS_FILL_ARGS)
>  			error = 0;
>  			break;
>  		}
> +		vm_map_lock_read(map);
> +		if (last_timestamp + 1 != map->timestamp) {
> +			/*
> +			 * Look again for the entry because the map was
> +			 * modified while it was unlocked.  Specifically,
> +			 * the entry may have been clipped, merged, or deleted.
> +			 */
> +			vm_map_lookup_entry(map, e_end - 1, &tmp_entry);
> +			entry = tmp_entry;
> +		}
>  	}
>  	vm_map_unlock_read(map);
>  	return (error);
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