Re: [PATCH 2/3] cnic: Don't take cnic_dev_lock in cnic_alloc_uio_rings()
From: Neil Horman <nhorman@tuxdriver.com>
Date: 2014-05-31 13:07:13
On Fri, May 30, 2014 at 04:18:42PM -0700, Michael Chan wrote:
We are allocating memory with GFP_KERNEL under spinlock. Since this is the only call manipulating the cnic_udev_list and it is always under rtnl_lock, cnic_dev_lock can be safely removed.
I don't think this is accurate. cnic_alloc_uio_rings seems to protect the list with cnic_dev_lock, but has several paths (those calling ->alloc_resc()), that never hold the rtnl_lock. Neil
quoted hunk ↗ jump to hunk
Signed-off-by: Michael Chan <mchan@broadcom.com> --- drivers/net/ethernet/broadcom/cnic.c | 6 ------ 1 files changed, 0 insertions(+), 6 deletions(-)diff --git a/drivers/net/ethernet/broadcom/cnic.c b/drivers/net/ethernet/broadcom/cnic.c index 7f40a2c..4ebab75 100644 --- a/drivers/net/ethernet/broadcom/cnic.c +++ b/drivers/net/ethernet/broadcom/cnic.c@@ -1039,21 +1039,17 @@ static int cnic_alloc_uio_rings(struct cnic_dev *dev, int pages) struct cnic_local *cp = dev->cnic_priv; struct cnic_uio_dev *udev; - read_lock(&cnic_dev_lock); list_for_each_entry(udev, &cnic_udev_list, list) { if (udev->pdev == dev->pcidev) { udev->dev = dev; if (__cnic_alloc_uio_rings(udev, pages)) { udev->dev = NULL; - read_unlock(&cnic_dev_lock); return -ENOMEM; } cp->udev = udev; - read_unlock(&cnic_dev_lock); return 0; } } - read_unlock(&cnic_dev_lock); udev = kzalloc(sizeof(struct cnic_uio_dev), GFP_ATOMIC); if (!udev)@@ -1067,9 +1063,7 @@ static int cnic_alloc_uio_rings(struct cnic_dev *dev, int pages) if (__cnic_alloc_uio_rings(udev, pages)) goto err_udev; - write_lock(&cnic_dev_lock); list_add(&udev->list, &cnic_udev_list); - write_unlock(&cnic_dev_lock); pci_dev_get(udev->pdev);-- 1.7.1