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authorStefan Richter <stefanr@s5r6.in-berlin.de>2007-08-25 08:08:19 -0400
committerStefan Richter <stefanr@s5r6.in-berlin.de>2007-10-16 18:00:05 -0400
commitee71c2f9ee85117e41ef87357ed8f75d29369b98 (patch)
tree9bb749909370ec732ed730ca80553908913156af /drivers/firewire/fw-ohci.c
parentdf8ec2490fed5dd23316bbb2c2e90e59e7d37126 (diff)
firewire: fw-ohci: enforce read order for selfID generation
It seems unlikely, but access to self_id_cpu[0] could at least in theory be deferred until after the loop over self_id_cpu[1..n] or even after the subsequent reg_read. Enforce the desired order by a read barrier. Also prevent the reg_read from being reordered relative to the for loop. This isn't necessary if the loop's conditional printk counts as an implicit barrier, but better make it explicit. (self_id_cpu[] is a coherent DMA buffer.) Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Diffstat (limited to 'drivers/firewire/fw-ohci.c')
-rw-r--r--drivers/firewire/fw-ohci.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/firewire/fw-ohci.c b/drivers/firewire/fw-ohci.c
index e14c1ca7813e..a7947baeee48 100644
--- a/drivers/firewire/fw-ohci.c
+++ b/drivers/firewire/fw-ohci.c
@@ -30,6 +30,7 @@
30 30
31#include <asm/uaccess.h> 31#include <asm/uaccess.h>
32#include <asm/semaphore.h> 32#include <asm/semaphore.h>
33#include <asm/system.h>
33 34
34#include "fw-transaction.h" 35#include "fw-transaction.h"
35#include "fw-ohci.h" 36#include "fw-ohci.h"
@@ -926,12 +927,14 @@ static void bus_reset_tasklet(unsigned long data)
926 927
927 self_id_count = (reg_read(ohci, OHCI1394_SelfIDCount) >> 3) & 0x3ff; 928 self_id_count = (reg_read(ohci, OHCI1394_SelfIDCount) >> 3) & 0x3ff;
928 generation = (le32_to_cpu(ohci->self_id_cpu[0]) >> 16) & 0xff; 929 generation = (le32_to_cpu(ohci->self_id_cpu[0]) >> 16) & 0xff;
930 rmb();
929 931
930 for (i = 1, j = 0; j < self_id_count; i += 2, j++) { 932 for (i = 1, j = 0; j < self_id_count; i += 2, j++) {
931 if (ohci->self_id_cpu[i] != ~ohci->self_id_cpu[i + 1]) 933 if (ohci->self_id_cpu[i] != ~ohci->self_id_cpu[i + 1])
932 fw_error("inconsistent self IDs\n"); 934 fw_error("inconsistent self IDs\n");
933 ohci->self_id_buffer[j] = le32_to_cpu(ohci->self_id_cpu[i]); 935 ohci->self_id_buffer[j] = le32_to_cpu(ohci->self_id_cpu[i]);
934 } 936 }
937 rmb();
935 938
936 /* 939 /*
937 * Check the consistency of the self IDs we just read. The 940 * Check the consistency of the self IDs we just read. The