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    Subject[PATCH -v2] EDAC: Fix lockdep splat
    Date
    From: Borislav Petkov <bp@suse.de>

    Fix the following:

    BUG: key ffff88043bdd0330 not in .data!
    ------------[ cut here ]------------
    WARNING: at kernel/lockdep.c:2987 lockdep_init_map+0x565/0x5a0()
    DEBUG_LOCKS_WARN_ON(1)
    Modules linked in: glue_helper sb_edac(+) edac_core snd acpi_cpufreq lrw gf128mul ablk_helper iTCO_wdt evdev i2c_i801 dcdbas button cryptd pcspkr iTCO_vendor_support usb_common lpc_ich mfd_core soundcore mperf processor microcode
    CPU: 2 PID: 599 Comm: modprobe Not tainted 3.10.0 #1
    Hardware name: Dell Inc. Precision T3600/0PTTT9, BIOS A08 01/24/2013
    0000000000000009 ffff880439a1d920 ffffffff8160a9a9 ffff880439a1d958
    ffffffff8103d9e0 ffff88043af4a510 ffffffff81a16e11 0000000000000000
    ffff88043bdd0330 0000000000000000 ffff880439a1d9b8 ffffffff8103dacc
    Call Trace:
    dump_stack
    warn_slowpath_common
    warn_slowpath_fmt
    lockdep_init_map
    ? trace_hardirqs_on_caller
    ? trace_hardirqs_on
    debug_mutex_init
    __mutex_init
    bus_register
    edac_create_sysfs_mci_device
    edac_mc_add_mc
    sbridge_probe
    pci_device_probe
    driver_probe_device
    __driver_attach
    ? driver_probe_device
    bus_for_each_dev
    driver_attach
    bus_add_driver
    driver_register
    __pci_register_driver
    ? 0xffffffffa0010fff
    sbridge_init
    ? 0xffffffffa0010fff
    do_one_initcall
    load_module
    ? unset_module_init_ro_nx
    SyS_init_module
    tracesys
    ---[ end trace d24a70b0d3ddf733 ]---
    EDAC MC0: Giving out device to 'sbridge_edac.c' 'Sandy Bridge Socket#0': DEV 0000:3f:0e.0
    EDAC sbridge: Driver loaded.

    What happens is that bus_register needs a statically allocated lock_key
    because the last is handed in to lockdep. However, struct mem_ctl_info
    embeds struct bus_type (the whole struct, not a pointer to it) and the
    whole thing gets dynamically allocated.

    Fix this by using a statically allocated struct bus_type for the MC bus.

    Cc: Mauro Carvalho Chehab <mchehab@infradead.org>
    Cc: Markus Trippelsdorf <markus@trippelsdorf.de>
    Signed-off-by: Borislav Petkov <bp@suse.de>
    ---
    drivers/edac/edac_mc.c | 9 +++++++++
    drivers/edac/edac_mc_sysfs.c | 28 +++++++++++++++-------------
    drivers/edac/i5100_edac.c | 2 +-
    include/linux/edac.h | 7 ++++++-
    4 files changed, 31 insertions(+), 15 deletions(-)

    diff --git a/drivers/edac/edac_mc.c b/drivers/edac/edac_mc.c
    index 27e86d938262..c55ad285c285 100644
    --- a/drivers/edac/edac_mc.c
    +++ b/drivers/edac/edac_mc.c
    @@ -48,6 +48,8 @@ static LIST_HEAD(mc_devices);
    */
    static void const *edac_mc_owner;

    +static struct bus_type mc_bus[EDAC_MAX_MCS];
    +
    unsigned edac_dimm_info_location(struct dimm_info *dimm, char *buf,
    unsigned len)
    {
    @@ -723,6 +725,11 @@ int edac_mc_add_mc(struct mem_ctl_info *mci)
    int ret = -EINVAL;
    edac_dbg(0, "\n");

    + if (mci->mc_idx >= EDAC_MAX_MCS) {
    + pr_warn_once("Too many memory controllers: %d\n", mci->mc_idx);
    + return ret;
    + }
    +
    #ifdef CONFIG_EDAC_DEBUG
    if (edac_debug_level >= 3)
    edac_mc_dump_mci(mci);
    @@ -762,6 +769,8 @@ int edac_mc_add_mc(struct mem_ctl_info *mci)
    /* set load time so that error rate can be tracked */
    mci->start_time = jiffies;

    + mci->bus = &mc_bus[mci->mc_idx];
    +
    if (edac_create_sysfs_mci_device(mci)) {
    edac_mc_printk(mci, KERN_WARNING,
    "failed to create sysfs device\n");
    diff --git a/drivers/edac/edac_mc_sysfs.c b/drivers/edac/edac_mc_sysfs.c
    index ef15a7e613bc..e7c32c4f7837 100644
    --- a/drivers/edac/edac_mc_sysfs.c
    +++ b/drivers/edac/edac_mc_sysfs.c
    @@ -370,7 +370,7 @@ static int edac_create_csrow_object(struct mem_ctl_info *mci,
    return -ENODEV;

    csrow->dev.type = &csrow_attr_type;
    - csrow->dev.bus = &mci->bus;
    + csrow->dev.bus = mci->bus;
    device_initialize(&csrow->dev);
    csrow->dev.parent = &mci->dev;
    csrow->mci = mci;
    @@ -605,7 +605,7 @@ static int edac_create_dimm_object(struct mem_ctl_info *mci,
    dimm->mci = mci;

    dimm->dev.type = &dimm_attr_type;
    - dimm->dev.bus = &mci->bus;
    + dimm->dev.bus = mci->bus;
    device_initialize(&dimm->dev);

    dimm->dev.parent = &mci->dev;
    @@ -975,11 +975,13 @@ int edac_create_sysfs_mci_device(struct mem_ctl_info *mci)
    * The memory controller needs its own bus, in order to avoid
    * namespace conflicts at /sys/bus/edac.
    */
    - mci->bus.name = kasprintf(GFP_KERNEL, "mc%d", mci->mc_idx);
    - if (!mci->bus.name)
    + mci->bus->name = kasprintf(GFP_KERNEL, "mc%d", mci->mc_idx);
    + if (!mci->bus->name)
    return -ENOMEM;
    - edac_dbg(0, "creating bus %s\n", mci->bus.name);
    - err = bus_register(&mci->bus);
    +
    + edac_dbg(0, "creating bus %s\n", mci->bus->name);
    +
    + err = bus_register(mci->bus);
    if (err < 0)
    return err;

    @@ -988,7 +990,7 @@ int edac_create_sysfs_mci_device(struct mem_ctl_info *mci)
    device_initialize(&mci->dev);

    mci->dev.parent = mci_pdev;
    - mci->dev.bus = &mci->bus;
    + mci->dev.bus = mci->bus;
    dev_set_name(&mci->dev, "mc%d", mci->mc_idx);
    dev_set_drvdata(&mci->dev, mci);
    pm_runtime_forbid(&mci->dev);
    @@ -997,8 +999,8 @@ int edac_create_sysfs_mci_device(struct mem_ctl_info *mci)
    err = device_add(&mci->dev);
    if (err < 0) {
    edac_dbg(1, "failure: create device %s\n", dev_name(&mci->dev));
    - bus_unregister(&mci->bus);
    - kfree(mci->bus.name);
    + bus_unregister(mci->bus);
    + kfree(mci->bus->name);
    return err;
    }

    @@ -1064,8 +1066,8 @@ fail:
    }
    fail2:
    device_unregister(&mci->dev);
    - bus_unregister(&mci->bus);
    - kfree(mci->bus.name);
    + bus_unregister(mci->bus);
    + kfree(mci->bus->name);
    return err;
    }

    @@ -1098,8 +1100,8 @@ void edac_unregister_sysfs(struct mem_ctl_info *mci)
    {
    edac_dbg(1, "Unregistering device %s\n", dev_name(&mci->dev));
    device_unregister(&mci->dev);
    - bus_unregister(&mci->bus);
    - kfree(mci->bus.name);
    + bus_unregister(mci->bus);
    + kfree(mci->bus->name);
    }

    static void mc_attr_release(struct device *dev)
    diff --git a/drivers/edac/i5100_edac.c b/drivers/edac/i5100_edac.c
    index 1b635178cc44..157b934e8ce3 100644
    --- a/drivers/edac/i5100_edac.c
    +++ b/drivers/edac/i5100_edac.c
    @@ -974,7 +974,7 @@ static int i5100_setup_debugfs(struct mem_ctl_info *mci)
    if (!i5100_debugfs)
    return -ENODEV;

    - priv->debugfs = debugfs_create_dir(mci->bus.name, i5100_debugfs);
    + priv->debugfs = debugfs_create_dir(mci->bus->name, i5100_debugfs);

    if (!priv->debugfs)
    return -ENOMEM;
    diff --git a/include/linux/edac.h b/include/linux/edac.h
    index 0b763276f619..5c6d7fbaf89e 100644
    --- a/include/linux/edac.h
    +++ b/include/linux/edac.h
    @@ -622,7 +622,7 @@ struct edac_raw_error_desc {
    */
    struct mem_ctl_info {
    struct device dev;
    - struct bus_type bus;
    + struct bus_type *bus;

    struct list_head link; /* for global list of mem_ctl_info structs */

    @@ -742,4 +742,9 @@ struct mem_ctl_info {
    #endif
    };

    +/*
    + * Maximum number of memory controllers in the coherent fabric.
    + */
    +#define EDAC_MAX_MCS 16
    +
    #endif
    --
    1.8.3


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