From: John Feeney <jfeeney@redhat.com>
Date: Tue, 16 Sep 2008 15:50:48 -0400
Subject: [pci] allow multiple calls to pcim_enable_device
Message-id: 48D00E18.5080601@redhat.com
O-Subject: [RHEL5.3 PATCH] Allow multiple calls to pcim_enable_device()
Bugzilla: 462500
RH-Acked-by: Prarit Bhargava <prarit@redhat.com>
RH-Acked-by: David Milburn <dmilburn@redhat.com>
RH-Acked-by: Alan Cox <alan@redhat.com>

bugzilla 462500
BUG: warning when pata_sil680 loaded
http://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=462500

Description of problem:
When booting a system with a DRAC4, the following warning is output:

BUG: warning at drivers/pci/pci.c:727/pcim_enable_device() (Not tainted)
[<c04f110a>] pcim_enable_device+0x7b/0x97
[<f88ddf5c>] ata_pci_sff_init_one+0x62/0xe4 [libata]
[<c05532ab>] __driver_attach+0x0/0x6b
[<f892343c>] sil680_init_one+0x1e9/0x1f8 [pata_sil680]
[<c04f2d64>] pci_device_probe+0x36/0x57
[<c05531fe>] driver_probe_device+0x42/0x92
[<c05532ef>] __driver_attach+0x44/0x6b
[<c0552c29>] bus_for_each_dev+0x37/0x59
[<c0553149>] driver_attach+0x11/0x13
[<c05532ab>] __driver_attach+0x0/0x6b
[<c0552931>] bus_add_driver+0x64/0xfd
[<c04f2e89>] __pci_register_driver+0x3e/0x58
[<c043f238>] sys_init_module+0x1ae0/0x1c95
[<c04ee980>] pci_bus_read_config_byte+0x0/0x58
[<c0614d4f>] do_page_fault+0x31e/0x5d3
[<c0404ead>] sysenter_past_esp+0x56/0x79

Prarit found the code path to be:
drivers/ata/pata_sil680.c: sil680_init_one(): line 390
use_ioports:
       return ata_pci_sff_init_one(pdev, ppi, &sil680_sht, NULL);

which does
drivers/ata/libata-sff.c: ata_pci_sff_init_one(): line 296
       rc = pcim_enable_device(pdev);
       if (rc)
               goto out;

Since dr->enabled = 1, we hit the WARN_ON call in pcim_enable_device(),
drivers/pci/pci.c: pcim_enable_device(): line 727
       WARN_ON(!!dr->enabled);

Solution:
Upstream has solved this by allowing multiple calls to pcim_enable_device()
so allow multiple calls to pcim_enable_device().

Note: This is dependent upon the patch for bz459197 (compile pata_sil680)
as well as David Milburn's SATA update patch.

Testing:
Prarit tested it successfully on dell-pe830-02.

Acks would be appreciated.

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 4139912..2e7bc75 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -724,7 +724,8 @@ int pcim_enable_device(struct pci_dev *pdev)
 	dr = get_pci_dr(pdev);
 	if (unlikely(!dr))
 		return -ENOMEM;
-	WARN_ON(!!dr->enabled);
+	if (dr->enabled)
+		return 0;
 
 	rc = pci_enable_device(pdev);
 	if (!rc) {