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From:   =?UTF-8?q?=C3=8D=C3=B1igo=20Huguet?= <ihuguet@redhat.com>
To:     ecree.xilinx@gmail.com, habetsm.xilinx@gmail.com,
        davem@davemloft.net, kuba@kernel.org
Cc:     netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        ihuguet@redhat.com, ivecera@redhat.com
Subject: [PATCH 1/4] sfc: avoid double pci_remove of VFs
Date:   Mon, 21 Jun 2021 17:32:35 +0200
Message-Id: <20210621153238.13147-1-ihuguet@redhat.com>
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If pci_remove was called for a PF with VFs, the removal of the VFs was
called twice from efx_ef10_sriov_fini: one directly with pci_driver->remove
and another implicit by calling pci_disable_sriov, which also perform
the VFs remove. This was leading to crashing the kernel on the second
attempt.

Given that pci_disable_sriov already calls to pci remove function, get
rid of the direct call to pci_driver->remove from the driver.

2 different ways to trigger the bug:
- Create one or more VFs, then attach the PF to a virtual machine (at
  least with qemu/KVM)
- Create one or more VFs, then remove the PF with:
  echo 1 > /sys/bus/pci/devices/PF_PCI_ID/remove

Removing sfc module does not trigger the error, at least for me, because
it removes the VF first, and then the PF.

Example of a log with the error:
    list_del corruption, ffff967fd20a8ad0->next is LIST_POISON1 (dead000000000100)
    ------------[ cut here ]------------
    kernel BUG at lib/list_debug.c:47!
    [...trimmed...]
    RIP: 0010:__list_del_entry_valid.cold.1+0x12/0x4c
    [...trimmed...]
    Call Trace:
    efx_dissociate+0x1f/0x140 [sfc]
    efx_pci_remove+0x27/0x150 [sfc]
    pci_device_remove+0x3b/0xc0
    device_release_driver_internal+0x103/0x1f0
    pci_stop_bus_device+0x69/0x90
    pci_stop_and_remove_bus_device+0xe/0x20
    pci_iov_remove_virtfn+0xba/0x120
    sriov_disable+0x2f/0xe0
    efx_ef10_pci_sriov_disable+0x52/0x80 [sfc]
    ? pcie_aer_is_native+0x12/0x40
    efx_ef10_sriov_fini+0x72/0x110 [sfc]
    efx_pci_remove+0x62/0x150 [sfc]
    pci_device_remove+0x3b/0xc0
    device_release_driver_internal+0x103/0x1f0
    unbind_store+0xf6/0x130
    kernfs_fop_write+0x116/0x190
    vfs_write+0xa5/0x1a0
    ksys_write+0x4f/0xb0
    do_syscall_64+0x5b/0x1a0
    entry_SYSCALL_64_after_hwframe+0x65/0xca

Signed-off-by: Íñigo Huguet <ihuguet@redhat.com>
---
 drivers/net/ethernet/sfc/ef10_sriov.c | 10 +---------
 1 file changed, 1 insertion(+), 9 deletions(-)

diff --git a/drivers/net/ethernet/sfc/ef10_sriov.c b/drivers/net/ethernet/sfc/ef10_sriov.c
index 21fa6c0e8873..a5d28b0f75ba 100644
--- a/drivers/net/ethernet/sfc/ef10_sriov.c
+++ b/drivers/net/ethernet/sfc/ef10_sriov.c
@@ -439,7 +439,6 @@ int efx_ef10_sriov_init(struct efx_nic *efx)
 void efx_ef10_sriov_fini(struct efx_nic *efx)
 {
 	struct efx_ef10_nic_data *nic_data = efx->nic_data;
-	unsigned int i;
 	int rc;
 
 	if (!nic_data->vf) {
@@ -449,14 +448,7 @@ void efx_ef10_sriov_fini(struct efx_nic *efx)
 		return;
 	}
 
-	/* Remove any VFs in the host */
-	for (i = 0; i < efx->vf_count; ++i) {
-		struct efx_nic *vf_efx = nic_data->vf[i].efx;
-
-		if (vf_efx)
-			vf_efx->pci_dev->driver->remove(vf_efx->pci_dev);
-	}
-
+	/* Disable SRIOV and remove any VFs in the host */
 	rc = efx_ef10_pci_sriov_disable(efx, true);
 	if (rc)
 		netif_dbg(efx, drv, efx->net_dev,
-- 
2.31.1