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authorStefan Richter <stefanr@s5r6.in-berlin.de>2006-07-23 22:12:00 +0200
committerStefan Richter <stefanr@s5r6.in-berlin.de>2006-09-17 19:19:25 +0200
commitcc078189125db84a85a3bbb82df788b84fc68aa1 (patch)
tree223a5db571c2717fac380df21f3ee56f7c395728 /drivers/ieee1394/sbp2.h
parent9154df538fa044ac2b729ae5c6c47cae09e6977f (diff)
downloadlinux-cc078189125db84a85a3bbb82df788b84fc68aa1.tar.bz2
ieee1394: sbp2: safer last_orb and next_ORB handling
The sbp2 initiator has two ways to tell a target's fetch agent about new command ORBs: - Write the ORB's address to the ORB_POINTER register. This must not be done while the fetch agent is active. - Put the ORB's address into the previously submitted ORB's next_ORB field and write to the DOORBELL register. This may be done while the fetch agent is active or suspended. It must not be done while the fetch agent is in reset state. Sbp2 has a last_orb pointer which indicates in what way a new command should be announced. That pointer is concurrently accessed at various occasions. Furthermore, initiator and target are accessing the next_ORB field of ORBs concurrently and asynchronously. This patch does: - Protect all initiator accesses to last_orb by sbp2_command_orb_lock. - Add pci_dma_sync_single_for_device before a previously submitted ORB's next_ORB field is overwritten. - Insert a memory barrier between when next_ORB_lo and next_ORB_hi are overwritten. Next_ORB_hi must not be updated before next_ORB_lo. - Remove the rather unspecific and now superfluous qualifier "volatile" from the next_ORB fields. - Add comments on how last_orb is connected with what is known about the target's fetch agent's state. Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Diffstat (limited to 'drivers/ieee1394/sbp2.h')
-rw-r--r--drivers/ieee1394/sbp2.h4
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/ieee1394/sbp2.h b/drivers/ieee1394/sbp2.h
index b22ce1aa8fe4..dd80906e8a92 100644
--- a/drivers/ieee1394/sbp2.h
+++ b/drivers/ieee1394/sbp2.h
@@ -46,8 +46,8 @@
#define ORB_SET_DIRECTION(value) ((value & 0x1) << 27)
struct sbp2_command_orb {
- volatile u32 next_ORB_hi;
- volatile u32 next_ORB_lo;
+ u32 next_ORB_hi;
+ u32 next_ORB_lo;
u32 data_descriptor_hi;
u32 data_descriptor_lo;
u32 misc;