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    Subject[PATCH 4.18 107/235] ipmi: Fix I2C client removal in the SSIF driver
    Date
    4.18-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Corey Minyard <cminyard@mvista.com>

    commit 0745dde62835be7e2afe62fcdb482fcad79cb743 upstream.

    The SSIF driver was removing any client that came in through the
    platform interface, but it should only remove clients that it
    added. On a failure in the probe function, this could result
    in the following oops when the driver is removed and the
    client gets unregistered twice:

    CPU: 107 PID: 30266 Comm: rmmod Not tainted 4.18.0+ #80
    Hardware name: Cavium Inc. Saber/Saber, BIOS Cavium reference firmware version 7.0 08/04/2018
    pstate: 60400009 (nZCv daif +PAN -UAO)
    pc : kernfs_find_ns+0x28/0x120
    lr : kernfs_find_and_get_ns+0x40/0x60
    sp : ffff00002310fb50
    x29: ffff00002310fb50 x28: ffff800a8240f800
    x27: 0000000000000000 x26: 0000000000000000
    x25: 0000000056000000 x24: ffff000009073000
    x23: ffff000008998b38 x22: 0000000000000000
    x21: ffff800ed86de820 x20: 0000000000000000
    x19: ffff00000913a1d8 x18: 0000000000000000
    x17: 0000000000000000 x16: 0000000000000000
    x15: 0000000000000000 x14: 5300737265766972
    x13: 643d4d4554535953 x12: 0000000000000030
    x11: 0000000000000030 x10: 0101010101010101
    x9 : ffff800ea06cc3f9 x8 : 0000000000000000
    x7 : 0000000000000141 x6 : ffff000009073000
    x5 : ffff800adb706b00 x4 : 0000000000000000
    x3 : 00000000ffffffff x2 : 0000000000000000
    x1 : ffff000008998b38 x0 : ffff000008356760
    Process rmmod (pid: 30266, stack limit = 0x00000000e218418d)
    Call trace:
    kernfs_find_ns+0x28/0x120
    kernfs_find_and_get_ns+0x40/0x60
    sysfs_unmerge_group+0x2c/0x6c
    dpm_sysfs_remove+0x34/0x70
    device_del+0x58/0x30c
    device_unregister+0x30/0x7c
    i2c_unregister_device+0x84/0x90 [i2c_core]
    ssif_platform_remove+0x38/0x98 [ipmi_ssif]
    platform_drv_remove+0x2c/0x6c
    device_release_driver_internal+0x168/0x1f8
    driver_detach+0x50/0xbc
    bus_remove_driver+0x74/0xe8
    driver_unregister+0x34/0x5c
    platform_driver_unregister+0x20/0x2c
    cleanup_ipmi_ssif+0x50/0xd82c [ipmi_ssif]
    __arm64_sys_delete_module+0x1b4/0x220
    el0_svc_handler+0x104/0x160
    el0_svc+0x8/0xc
    Code: aa1e03e0 aa0203f6 aa0103f7 d503201f (7940e280)
    ---[ end trace 09f0e34cce8e2d8c ]---
    Kernel panic - not syncing: Fatal exception
    SMP: stopping secondary CPUs
    Kernel Offset: disabled
    CPU features: 0x23800c38

    So track the clients that the SSIF driver adds and only remove
    those.

    Reported-by: George Cherian <george.cherian@cavium.com>
    Signed-off-by: Corey Minyard <cminyard@mvista.com>
    Tested-by: George Cherian <george.cherian@cavium.com>
    Cc: <stable@vger.kernel.org> # 4.14.x
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    drivers/char/ipmi/ipmi_ssif.c | 17 ++++++-----------
    1 file changed, 6 insertions(+), 11 deletions(-)

    --- a/drivers/char/ipmi/ipmi_ssif.c
    +++ b/drivers/char/ipmi/ipmi_ssif.c
    @@ -181,6 +181,8 @@ struct ssif_addr_info {
    struct device *dev;
    struct i2c_client *client;

    + struct i2c_client *added_client;
    +
    struct mutex clients_mutex;
    struct list_head clients;

    @@ -1641,15 +1643,7 @@ static int ssif_probe(struct i2c_client

    out:
    if (rv) {
    - /*
    - * Note that if addr_info->client is assigned, we
    - * leave it. The i2c client hangs around even if we
    - * return a failure here, and the failure here is not
    - * propagated back to the i2c code. This seems to be
    - * design intent, strange as it may be. But if we
    - * don't leave it, ssif_platform_remove will not remove
    - * the client like it should.
    - */
    + addr_info->client = NULL;
    dev_err(&client->dev, "Unable to start IPMI SSIF: %d\n", rv);
    kfree(ssif_info);
    }
    @@ -1669,7 +1663,8 @@ static int ssif_adapter_handler(struct d
    if (adev->type != &i2c_adapter_type)
    return 0;

    - i2c_new_device(to_i2c_adapter(adev), &addr_info->binfo);
    + addr_info->added_client = i2c_new_device(to_i2c_adapter(adev),
    + &addr_info->binfo);

    if (!addr_info->adapter_name)
    return 1; /* Only try the first I2C adapter by default. */
    @@ -1842,7 +1837,7 @@ static int ssif_platform_remove(struct p
    return 0;

    mutex_lock(&ssif_infos_mutex);
    - i2c_unregister_device(addr_info->client);
    + i2c_unregister_device(addr_info->added_client);

    list_del(&addr_info->link);
    kfree(addr_info);

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