On Fri, 2017-01-06 at 23:28 +0000, Tantilov, Emil S wrote: > >-----Original Message----- > >From: Intel-wired-lan [mailto:intel-wired-lan-bounces@xxxxxxxxxxxxxxxx] On > >Behalf Of Greg > >Sent: Friday, January 06, 2017 3:18 PM > >To: Tantilov, Emil S <emil.s.tantilov@xxxxxxxxx> > >Cc: linux-pci@xxxxxxxxxxxxxxx; intel-wired-lan@xxxxxxxxxxxxxxxx; linux- > >kernel@xxxxxxxxxxxxxxx; netdev@xxxxxxxxxxxxxxx > >Subject: Re: [Intel-wired-lan] [PATCH v2] PCI: lock each enable/disable > >num_vfs operation in sysfs > > > >On Fri, 2017-01-06 at 13:59 -0800, Emil Tantilov wrote: > >> Enabling/disabling SRIOV via sysfs by echo-ing multiple values > >> simultaneously: > >> > >> echo 63 > /sys/class/net/ethX/device/sriov_numvfs& > >> echo 63 > /sys/class/net/ethX/device/sriov_numvfs > >> > >> sleep 5 > >> > >> echo 0 > /sys/class/net/ethX/device/sriov_numvfs& > >> echo 0 > /sys/class/net/ethX/device/sriov_numvfs > >> > >> Results in the following bug: > >> > >> kernel BUG at drivers/pci/iov.c:495! > >> invalid opcode: 0000 [#1] SMP > >> CPU: 1 PID: 8050 Comm: bash Tainted: G W 4.9.0-rc7-net-next #2092 > >> RIP: 0010:[<ffffffff813b1647>] > >> [<ffffffff813b1647>] pci_iov_release+0x57/0x60 > >> > >> Call Trace: > >> [<ffffffff81391726>] pci_release_dev+0x26/0x70 > >> [<ffffffff8155be6e>] device_release+0x3e/0xb0 > >> [<ffffffff81365ee7>] kobject_cleanup+0x67/0x180 > >> [<ffffffff81365d9d>] kobject_put+0x2d/0x60 > >> [<ffffffff8155bc27>] put_device+0x17/0x20 > >> [<ffffffff8139c08a>] pci_dev_put+0x1a/0x20 > >> [<ffffffff8139cb6b>] pci_get_dev_by_id+0x5b/0x90 > >> [<ffffffff8139cca5>] pci_get_subsys+0x35/0x40 > >> [<ffffffff8139ccc8>] pci_get_device+0x18/0x20 > >> [<ffffffff8139ccfb>] pci_get_domain_bus_and_slot+0x2b/0x60 > >> [<ffffffff813b09e7>] pci_iov_remove_virtfn+0x57/0x180 > >> [<ffffffff813b0b95>] pci_disable_sriov+0x65/0x140 > >> [<ffffffffa00a1af7>] ixgbe_disable_sriov+0xc7/0x1d0 [ixgbe] > >> [<ffffffffa00a1e9d>] ixgbe_pci_sriov_configure+0x3d/0x170 [ixgbe] > >> [<ffffffff8139d28c>] sriov_numvfs_store+0xdc/0x130 > >> ... > >> RIP [<ffffffff813b1647>] pci_iov_release+0x57/0x60 > >> > >> Use the existing mutex lock to protect each enable/disable operation. > >> > >> -v2: move the existing lock from protecting the config of the IOV bus > >> to protecting the writes to sriov_numvfs in sysfs without maintaining > >> a "locked" version of pci_iov_add/remove_virtfn(). > >> As suggested by Gavin Shan <gwshan@xxxxxxxxxxxxxxxxxx> > >> > >> CC: Alexander Duyck <alexander.h.duyck@xxxxxxxxx> > >> Signed-off-by: Emil Tantilov <emil.s.tantilov@xxxxxxxxx> > >> --- > >> drivers/pci/iov.c | 7 ------- > >> drivers/pci/pci-sysfs.c | 23 ++++++++++++++++------- > >> drivers/pci/pci.h | 2 +- > >> 3 files changed, 17 insertions(+), 15 deletions(-) > >> > >> diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c > >> index 4722782..2479ae8 100644 > >> --- a/drivers/pci/iov.c > >> +++ b/drivers/pci/iov.c > >> @@ -124,7 +124,6 @@ int pci_iov_add_virtfn(struct pci_dev *dev, int id, > >int reset) > >> struct pci_sriov *iov = dev->sriov; > >> struct pci_bus *bus; > >> > >> - mutex_lock(&iov->dev->sriov->lock); > >> bus = virtfn_add_bus(dev->bus, pci_iov_virtfn_bus(dev, id)); > >> if (!bus) > >> goto failed; > >> @@ -162,7 +161,6 @@ int pci_iov_add_virtfn(struct pci_dev *dev, int id, > >int reset) > >> __pci_reset_function(virtfn); > >> > >> pci_device_add(virtfn, virtfn->bus); > >> - mutex_unlock(&iov->dev->sriov->lock); > >> > >> pci_bus_add_device(virtfn); > >> sprintf(buf, "virtfn%u", id); > >> @@ -181,12 +179,10 @@ int pci_iov_add_virtfn(struct pci_dev *dev, int id, > >int reset) > >> sysfs_remove_link(&dev->dev.kobj, buf); > >> failed1: > >> pci_dev_put(dev); > >> - mutex_lock(&iov->dev->sriov->lock); > >> pci_stop_and_remove_bus_device(virtfn); > >> failed0: > >> virtfn_remove_bus(dev->bus, bus); > >> failed: > >> - mutex_unlock(&iov->dev->sriov->lock); > >> > >> return rc; > >> } > >> @@ -195,7 +191,6 @@ void pci_iov_remove_virtfn(struct pci_dev *dev, int > >id, int reset) > >> { > >> char buf[VIRTFN_ID_LEN]; > >> struct pci_dev *virtfn; > >> - struct pci_sriov *iov = dev->sriov; > >> > >> virtfn = pci_get_domain_bus_and_slot(pci_domain_nr(dev->bus), > >> pci_iov_virtfn_bus(dev, id), > >> @@ -218,10 +213,8 @@ void pci_iov_remove_virtfn(struct pci_dev *dev, int > >id, int reset) > >> if (virtfn->dev.kobj.sd) > >> sysfs_remove_link(&virtfn->dev.kobj, "physfn"); > >> > >> - mutex_lock(&iov->dev->sriov->lock); > >> pci_stop_and_remove_bus_device(virtfn); > >> virtfn_remove_bus(dev->bus, virtfn->bus); > >> - mutex_unlock(&iov->dev->sriov->lock); > >> > >> /* balance pci_get_domain_bus_and_slot() */ > >> pci_dev_put(virtfn); > >> diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c > >> index 0666287..25d010d 100644 > >> --- a/drivers/pci/pci-sysfs.c > >> +++ b/drivers/pci/pci-sysfs.c > >> @@ -472,6 +472,7 @@ static ssize_t sriov_numvfs_store(struct device *dev, > >> const char *buf, size_t count) > >> { > >> struct pci_dev *pdev = to_pci_dev(dev); > >> + struct pci_sriov *iov = pdev->sriov; > >> int ret; > >> u16 num_vfs; > >> > >> @@ -482,38 +483,46 @@ static ssize_t sriov_numvfs_store(struct device > >*dev, > >> if (num_vfs > pci_sriov_get_totalvfs(pdev)) > >> return -ERANGE; > >> > >> + mutex_lock(&iov->dev->sriov->lock); > >> + > >> if (num_vfs == pdev->sriov->num_VFs) > >> - return count; /* no change */ > >> + goto exit; > >> > >> /* is PF driver loaded w/callback */ > >> if (!pdev->driver || !pdev->driver->sriov_configure) { > >> dev_info(&pdev->dev, "Driver doesn't support SRIOV > >configuration via sysfs\n"); > >> - return -ENOSYS; > >> + ret = -ENOENT; > >> + goto exit; > > > >Hi Emil, > > > >Generally the patch looks fine to me - but I am wondering why the change > >from -ENOSYS TO -ENOENT? > > Because checkpatch was complaining that ENOSYS should only be used for > "invalid syscall nr". > > If you look at the discussion of the previous version of the patch you can > see the details there. Basically Gavin preferred ENOENT and I don't really > care so much (I kind of ran into this by accident as this patch does not need > to change the error code). Ah, OK. Thanks for the explanation! Tell all my old buddies there at Intel I said hi. Regards, - Greg > > Thanks, > Emil -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
