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    Subject[PATCH 2/2] ehea: fix possible DLPAR/mem deadlock
    Force serialization of userspace-triggered DLPAR/mem operations

    Signed-off-by: Thomas Klein <tklein@de.ibm.com>
    ---

    Patch created against 2.6.34-rc4

    diff -Nurp linux-2.6.34-rc4.orig//drivers/net/ehea/ehea.h linux-2.6.34-rc4//drivers/net/ehea/ehea.h
    --- linux-2.6.34-rc4.orig//drivers/net/ehea/ehea.h 2010-04-19 11:54:07.000000000 +0200
    +++ linux-2.6.34-rc4//drivers/net/ehea/ehea.h 2010-04-19 12:00:14.000000000 +0200
    @@ -40,7 +40,7 @@
    #include <asm/io.h>

    #define DRV_NAME "ehea"
    -#define DRV_VERSION "EHEA_0102"
    +#define DRV_VERSION "EHEA_0103"

    /* eHEA capability flags */
    #define DLPAR_PORT_ADD_REM 1
    diff -Nurp linux-2.6.34-rc4.orig//drivers/net/ehea/ehea_main.c linux-2.6.34-rc4//drivers/net/ehea/ehea_main.c
    --- linux-2.6.34-rc4.orig//drivers/net/ehea/ehea_main.c 2010-04-19 11:59:11.000000000 +0200
    +++ linux-2.6.34-rc4//drivers/net/ehea/ehea_main.c 2010-04-19 11:59:50.000000000 +0200
    @@ -2889,7 +2889,6 @@ static void ehea_rereg_mrs(struct work_s
    int ret, i;
    struct ehea_adapter *adapter;

    - mutex_lock(&dlpar_mem_lock);
    ehea_info("LPAR memory changed - re-initializing driver");

    list_for_each_entry(adapter, &adapter_list, list)
    @@ -2959,7 +2958,6 @@ static void ehea_rereg_mrs(struct work_s
    }
    ehea_info("re-initializing driver complete");
    out:
    - mutex_unlock(&dlpar_mem_lock);
    return;
    }

    @@ -3542,7 +3540,14 @@ void ehea_crash_handler(void)
    static int ehea_mem_notifier(struct notifier_block *nb,
    unsigned long action, void *data)
    {
    + int ret = NOTIFY_BAD;
    struct memory_notify *arg = data;
    +
    + if (!mutex_trylock(&dlpar_mem_lock)) {
    + ehea_info("ehea_mem_notifier must not be called parallelized");
    + goto out;
    + }
    +
    switch (action) {
    case MEM_CANCEL_OFFLINE:
    ehea_info("memory offlining canceled");
    @@ -3551,14 +3556,14 @@ static int ehea_mem_notifier(struct noti
    ehea_info("memory is going online");
    set_bit(__EHEA_STOP_XFER, &ehea_driver_flags);
    if (ehea_add_sect_bmap(arg->start_pfn, arg->nr_pages))
    - return NOTIFY_BAD;
    + goto out_unlock;
    ehea_rereg_mrs(NULL);
    break;
    case MEM_GOING_OFFLINE:
    ehea_info("memory is going offline");
    set_bit(__EHEA_STOP_XFER, &ehea_driver_flags);
    if (ehea_rem_sect_bmap(arg->start_pfn, arg->nr_pages))
    - return NOTIFY_BAD;
    + goto out_unlock;
    ehea_rereg_mrs(NULL);
    break;
    default:
    @@ -3566,8 +3571,12 @@ static int ehea_mem_notifier(struct noti
    }

    ehea_update_firmware_handles();
    + ret = NOTIFY_OK;

    - return NOTIFY_OK;
    +out_unlock:
    + mutex_unlock(&dlpar_mem_lock);
    +out:
    + return ret;
    }

    static struct notifier_block ehea_mem_nb = {

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