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Commit 1c8e71d7 authored by Douglas Gilbert's avatar Douglas Gilbert Committed by James Bottomley
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[SCSI] sg: do not set VM_IO flag on mmap-ed pages 

Further to the problem discussed in this post:
http://marc.theaimsgroup.com/?l=linux-scsi&m=112540053711489&w=2



It seems that the sg driver does not need to set the VM_IO flag
on pages that it memory maps to the user space since they are
not from the IO space. Ahmed Teirelbar <ahmed.teirelbar@adic.com>
wants the facility and has tested this patch as I have without
adverse effects.

The oops protection is still important. Some users really did
try and use dio transfers from the sg driver to memory mapped
IO space (on a video capture card if my memory serves) during the
lk 2.4 series. I'm not sure how successful it was but that will
now be politely refused in lk 2.6.13+ .

Changelog:
   - set the page flags for sg's reserved buffer mmap-ed
     to the user space to VM_RESERVED (rather than
     VM_RESERVED | VM_IO )

Signed-off-by: default avatarDouglas Gilbert <dougg@torque.net>
Signed-off-by: default avatarJames Bottomley <James.Bottomley@SteelEye.com>
parent 788ce43a

drivers/scsi/sg.c

+2 −2
Original line number Diff line number Diff line
@@ -61,7 +61,7 @@ static int sg_version_num = 30533; /* 2 digits for each component */ 


#ifdef CONFIG_SCSI_PROC_FS

#include <linux/proc_fs.h>

static char *sg_version_date = "20050901";

static char *sg_version_date = "20050908";



static int sg_proc_init(void);

static void sg_proc_cleanup(void);
@@ -1299,7 +1299,7 @@ sg_mmap(struct file *filp, struct vm_area_struct *vma) 
		sg_rb_correct4mmap(rsv_schp, 1);	/* do only once per fd lifetime */

		sfp->mmap_called = 1;

	}

	vma->vm_flags |= (VM_RESERVED | VM_IO);

	vma->vm_flags |= VM_RESERVED;

	vma->vm_private_data = sfp;

	vma->vm_ops = &sg_mmap_vm_ops;

	return 0;