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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: Douglas Gilbert <dougg@torque.net>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
This commit is contained in:
Douglas Gilbert 2005-09-09 17:18:57 +10:00 committed by James Bottomley
parent 788ce43aa1
commit 1c8e71d720
1 changed files with 2 additions and 2 deletions
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4
drivers/scsi/sg.c
View File

@ -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;