Re: [PATCH] lpfc: Avoid to disable pci_dev twice

From: Mike Qiu
Date: Wed Sep 10 2014 - 02:49:38 EST

On 08/28/2014 02:34 AM, James Smart wrote:
Mike,

Can you confirm - the "nulls" this patch correct are because the probe_one and error_detect threads are running concurrently, thus battling ?

If so - this fix looks insufficient and we should rework it.

Yes, it is. My patch is just a workaround for this bug.


Q: why are they allowed to run concurrently ? I could see this solved at the platform level to let probe_one finish before error_detect is called (and therefore stating error_detect only makes sense to call if probe_one was successful). It's also a much driver-friendly solution. I could see other drivers have much the same issue with concurrency and data structure teardown - and if locks aren't allowed in the error-detect path... it's not good.


I agree with you on this point, platform solution is much better. So maybe use a lock or a flag to show it is in such stat, this maybe also happens when driver is in remove stat.

Thanks,
Mike
-- james s



On 7/31/2014 10:16 PM, Mike Qiu wrote:
On 07/17/2014 02:32 PM, Mike Qiu wrote:


Hi, all

How about this patch ?

Any idea ?

In IBM Power servers, when hardware error occurs during probe
state, EEH subsystem will call driver's error_detected interface,
which will call pci_disable_device(). But driver's probe function also
call pci_disable_device() in this situation.

So pci_dev will be disabled twice:

Device lpfc disabling already-disabled device
------------[ cut here ]------------
WARNING: at drivers/pci/pci.c:1407
CPU: 0 PID: 8744 Comm: kworker/0:0 Tainted: G W 3.10.42-2002.pkvm2_1_1.6.ppc64 #1
Workqueue: events .work_for_cpu_fn
task: c00000274e3f5400 ti: c0000027d3958000 task.ti: c0000027d3958000
NIP: c000000000471b8c LR: c000000000471b88 CTR: c00000000043ebe0
REGS: c0000027d395b650 TRAP: 0700 Tainted: G W (3.10.42-2002.pkvm2_1_1.6.ppc64)
MSR: 9000000100029032 <SF,HV,EE,ME,IR,DR,RI> CR: 28b52b44 XER: 20000000
CFAR: c000000000879ab8 SOFTE: 1
...
NIP .pci_disable_device+0xcc/0xe0
LR .pci_disable_device+0xc8/0xe0
Call Trace:
.pci_disable_device+0xc8/0xe0 (unreliable)
.lpfc_disable_pci_dev+0x50/0x80 [lpfc]
.lpfc_pci_probe_one+0x870/0x21a0 [lpfc]
.local_pci_probe+0x68/0xb0
.work_for_cpu_fn+0x38/0x60
.process_one_work+0x1a4/0x4d0
.worker_thread+0x37c/0x490
.kthread+0xf0/0x100
.ret_from_kernel_thread+0x5c/0x80

Signed-off-by: Mike Qiu <qiudayu@xxxxxxxxxxxxxxxxxx>
---
drivers/scsi/lpfc/lpfc.h | 1 +
drivers/scsi/lpfc/lpfc_init.c | 59 +++++++++++++++++++++++++++++++++++++++----
2 files changed, 55 insertions(+), 5 deletions(-)

diff --git a/drivers/scsi/lpfc/lpfc.h b/drivers/scsi/lpfc/lpfc.h
index 434e903..0c7bad9 100644
--- a/drivers/scsi/lpfc/lpfc.h
+++ b/drivers/scsi/lpfc/lpfc.h
@@ -813,6 +813,7 @@ struct lpfc_hba {
#define VPD_MASK 0xf /* mask for any vpd data */

uint8_t soft_wwn_enable;
+ uint8_t probe_done;

struct timer_list fcp_poll_timer;
struct timer_list eratt_poll;
diff --git a/drivers/scsi/lpfc/lpfc_init.c b/drivers/scsi/lpfc/lpfc_init.c
index 06f9a5b..c2e67ae 100644
--- a/drivers/scsi/lpfc/lpfc_init.c
+++ b/drivers/scsi/lpfc/lpfc_init.c
@@ -9519,6 +9519,9 @@ lpfc_pci_probe_one_s3(struct pci_dev *pdev, const struct pci_device_id *pid)
}
}

+ /* Set the probe flag */
+ phba->probe_done = 1;
+
/* Perform post initialization setup */
lpfc_post_init_setup(phba);

@@ -9795,6 +9798,9 @@ lpfc_sli_prep_dev_for_recover(struct lpfc_hba *phba)
static void
lpfc_sli_prep_dev_for_reset(struct lpfc_hba *phba)
{
+ if (phba)
+ return;
+
lpfc_printf_log(phba, KERN_ERR, LOG_INIT,
"2710 PCI channel disable preparing for reset\n");

@@ -9812,7 +9818,8 @@ lpfc_sli_prep_dev_for_reset(struct lpfc_hba *phba)

/* Disable interrupt and pci device */
lpfc_sli_disable_intr(phba);
- pci_disable_device(phba->pcidev);
+ if (phba->probe_done && phba->pcidev)
+ pci_disable_device(phba->pcidev);
}

/**
@@ -10282,6 +10289,9 @@ lpfc_pci_probe_one_s4(struct pci_dev *pdev, const struct pci_device_id *pid)
goto out_disable_intr;
}

+ /* Set probe_done flag */
+ phba->probe_done = 1;
+
/* Log the current active interrupt mode */
phba->intr_mode = intr_mode;
lpfc_log_intr_mode(phba, intr_mode);
@@ -10544,6 +10554,9 @@ lpfc_sli4_prep_dev_for_recover(struct lpfc_hba *phba)
static void
lpfc_sli4_prep_dev_for_reset(struct lpfc_hba *phba)
{
+ if (!phba)
+ return;
+
lpfc_printf_log(phba, KERN_ERR, LOG_INIT,
"2826 PCI channel disable preparing for reset\n");

@@ -10562,7 +10575,9 @@ lpfc_sli4_prep_dev_for_reset(struct lpfc_hba *phba)
/* Disable interrupt and pci device */
lpfc_sli4_disable_intr(phba);
lpfc_sli4_queue_destroy(phba);
- pci_disable_device(phba->pcidev);
+
+ if (phba->probe_done && phba->pcidev)
+ pci_disable_device(phba->pcidev);
}

/**
@@ -10893,9 +10908,21 @@ static pci_ers_result_t
lpfc_io_error_detected(struct pci_dev *pdev, pci_channel_state_t state)
{
struct Scsi_Host *shost = pci_get_drvdata(pdev);
- struct lpfc_hba *phba = ((struct lpfc_vport *)shost->hostdata)->phba;
+ struct lpfc_hba *phba;
pci_ers_result_t rc = PCI_ERS_RESULT_DISCONNECT;

+ if (!shost)
+ /* Run here means it may during probe state and
+ * Scsi_Host has not been created and We can do nothing
+ * in this state so call for hotplug*/
+ return PCI_ERS_RESULT_NONE;
+
+ phba = ((struct lpfc_vport *)shost->hostdata)->phba;
+
+ if (!phba || !phba->probe_done)
+ /* Run here means it may during probe state */
+ return PCI_ERS_RESULT_NONE;
+
switch (phba->pci_dev_grp) {
case LPFC_PCI_DEV_LP:
rc = lpfc_io_error_detected_s3(pdev, state);
@@ -10930,9 +10957,20 @@ static pci_ers_result_t
lpfc_io_slot_reset(struct pci_dev *pdev)
{
struct Scsi_Host *shost = pci_get_drvdata(pdev);
- struct lpfc_hba *phba = ((struct lpfc_vport *)shost->hostdata)->phba;
+ struct lpfc_hba *phba;
pci_ers_result_t rc = PCI_ERS_RESULT_DISCONNECT;

+ if (!shost)
+ /* Run here means it may during probe state and
+ * Scsi_Host has not been created */
+ return PCI_ERS_RESULT_NONE;
+
+ phba = ((struct lpfc_vport *)shost->hostdata)->phba;
+
+ if (!phba || !phba->probe_done)
+ /* Run here means it may during probe state */
+ return PCI_ERS_RESULT_NONE;
+
switch (phba->pci_dev_grp) {
case LPFC_PCI_DEV_LP:
rc = lpfc_io_slot_reset_s3(pdev);
@@ -10963,7 +11001,18 @@ static void
lpfc_io_resume(struct pci_dev *pdev)
{
struct Scsi_Host *shost = pci_get_drvdata(pdev);
- struct lpfc_hba *phba = ((struct lpfc_vport *)shost->hostdata)->phba;
+ struct lpfc_hba *phba;
+
+ if (!shost)
+ /* Run here means it may during probe state and
+ * Scsi_Host has not been created */
+ return;
+
+ phba = ((struct lpfc_vport *)shost->hostdata)->phba;
+
+ if (!phba || !phba->probe_done)
+ /* Run here means it may during probe state */
+ return;

switch (phba->pci_dev_grp) {
case LPFC_PCI_DEV_LP:




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