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drivers/edac: mod race fix i82875p

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If ERRSTS indicates that there's no error then we don't need to bother reading
the other registers.

In addition to making the common case faster, this actually fixes a small race
where we don't see an error but we clear the error bits anyway, potentially
wiping away info on an error that happened in the interim (or where a CE
arrives between the first and second read of ERRSTS, causing us to falsely
claim "UE overwrote CE").

Signed-off-by: Jason Uhlenkott <juhlenko@akamai.com>
Signed-off-by: Douglas Thompson <dougthompson@xmission.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Jason Uhlenkott 2007-07-19 01:50:16 -07:00 committed by Linus Torvalds
parent b113a3f7e8
commit 654ede200f
1 changed files with 7 additions and 6 deletions
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13
drivers/edac/i82875p_edac.c
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@ -198,27 +198,28 @@ static void i82875p_get_error_info(struct mem_ctl_info *mci,
* overwritten by UE.
*/
pci_read_config_word(pdev, I82875P_ERRSTS, &info->errsts);
if (!(info->errsts & 0x0081))
return;
pci_read_config_dword(pdev, I82875P_EAP, &info->eap);
pci_read_config_byte(pdev, I82875P_DES, &info->des);
pci_read_config_byte(pdev, I82875P_DERRSYN, &info->derrsyn);
pci_read_config_word(pdev, I82875P_ERRSTS, &info->errsts2);
pci_write_bits16(pdev, I82875P_ERRSTS, 0x0081, 0x0081);
/*
* If the error is the same then we can for both reads then
* the first set of reads is valid. If there is a change then
* there is a CE no info and the second set of reads is valid
* and should be UE info.
*/
if (!(info->errsts2 & 0x0081))
return;
if ((info->errsts ^ info->errsts2) & 0x0081) {
pci_read_config_dword(pdev, I82875P_EAP, &info->eap);
pci_read_config_byte(pdev, I82875P_DES, &info->des);
pci_read_config_byte(pdev, I82875P_DERRSYN, &info->derrsyn);
}
pci_write_bits16(pdev, I82875P_ERRSTS, 0x0081, 0x0081);
}
static int i82875p_process_error_info(struct mem_ctl_info *mci,
@ -229,7 +230,7 @@ static int i82875p_process_error_info(struct mem_ctl_info *mci,
multi_chan = mci->csrows[0].nr_channels - 1;
if (!(info->errsts2 & 0x0081))
if (!(info->errsts & 0x0081))
return 0;
if (!handle_errors)