netdev - RE: fec_main: context imbalance in 'fec_set

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Date:	Thu, 9 Oct 2014 09:55:38 +0000
From:	"fugang.duan@...escale.com" <fugang.duan@...escale.com>
To:	Fabio Estevam <festevam@...il.com>,
	"Frank.Li@...escale.com" <Frank.Li@...escale.com>
CC:	"David S. Miller" <davem@...emloft.net>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"linux-sparse@...r.kernel.org" <linux-sparse@...r.kernel.org>
Subject: RE: fec_main: context imbalance in 'fec_set_features'

From: Fabio Estevam <festevam@...il.com> Sent: Thursday, October 02, 2014 8:16 AM
>To: Li Frank-B20596; Duan Fugang-B38611
>Cc: David S. Miller; netdev@...r.kernel.org; linux-sparse@...r.kernel.org
>Subject: fec_main: context imbalance in 'fec_set_features'
>
>Hi,
>
>sparse complains the following:
>
>drivers/net/ethernet/freescale/fec_main.c:2835:12: warning: context
>imbalance in 'fec_set_features' - different lock contexts for basic block
>
>The code looks like this:
>
>static int fec_set_features(struct net_device *netdev,
>    netdev_features_t features)
>{
>    struct fec_enet_private *fep = netdev_priv(netdev);
>    netdev_features_t changed = features ^ netdev->features;
>
>    /* Quiesce the device if necessary */
>    if (netif_running(netdev) && changed & FEATURES_NEED_QUIESCE) {
>        napi_disable(&fep->napi);
>        netif_tx_lock_bh(netdev);
>        fec_stop(netdev);
>    }
>
>    netdev->features = features;
>
>    /* Receive checksum has been changed */
>    if (changed & NETIF_F_RXCSUM) {
>        if (features & NETIF_F_RXCSUM)
>            fep->csum_flags |= FLAG_RX_CSUM_ENABLED;
>        else
>            fep->csum_flags &= ~FLAG_RX_CSUM_ENABLED;
>    }
>
>    /* Resume the device after updates */
>    if (netif_running(netdev) && changed & FEATURES_NEED_QUIESCE) {
>        fec_restart(netdev);
>        netif_tx_wake_all_queues(netdev);
>        netif_tx_unlock_bh(netdev);
>        napi_enable(&fep->napi);
>    }
>
>    return 0;
>}
>
>What would be the proper way to fix this warning?
>
>Thanks,
>
>Fabio Estevam

Hi, Fabio,

I run sparse and cannot get any warning.
1. git clone git://git.kernel.org/pub/scm/devel/sparse/sparse.git
   make
   make install
2. export PATH=$PATH:~/bin/
3. make kernel: make  -j16 ARCH=arm CROSS_COMPILE=arm-poky-linux-gnueabi- zImage C=2

Commit ID on David net tree: 28b7deae75642c51f097391765fd39ff0dd6ce95

The result:
  CHECK   fs/lockd/svc4proc.c
  CHECK   drivers/of/platform.c
  CHECK   drivers/input/touchscreen/tsc2007.c
  CHECK   drivers/mtd/nand/nand_timings.c
  CHECK   drivers/pci/probe.c
  CHECK   drivers/pci/host-bridge.c
  CHECK   drivers/pci/remove.c
drivers/mtd/nand/nand_timings.c:45:29: warning: constant 250000000000 is so big it is long long
  CHECK   drivers/mtd/nand/nand_ecc.c
  CHECK   drivers/mtd/nand/nand_ids.c
  CHECK   drivers/net/ethernet/freescale/fec_main.c
  CHECK   drivers/of/fdt.c
  CHECK   drivers/of/fdt_address.c
  CHECK   drivers/pci/pci.c
  CHECK   drivers/mtd/nand/mxc_nand.c
  CHECK   fs/notify/fsnotify.c
  CHECK   fs/notify/notification.c
  CHECK   fs/notify/group.c
  CHECK   fs/notify/inode_mark.c
  CHECK   drivers/net/ethernet/freescale/fec_ptp.c
  CHECK   fs/notify/mark.c
  CHECK   fs/notify/vfsmount_mark.c
drivers/pci/pci.c:35:5: warning: symbol 'isa_dma_bridge_buggy' was not declared. Should it be static?
drivers/pci/pci.c:4392:1: warning: symbol 'bus_attr_resource_alignment' was not declared. Should it be static?
  CHECK   fs/notify/fdinfo.c
  CHECK   drivers/pci/pci-driver.c
  CHECK   drivers/pci/search.c
  CHECK   drivers/pci/pci-sysfs.c
  CHECK   drivers/pci/rom.c
  CHECK   drivers/pci/setup-res.c

Regards,
Andy