• Vaibhav Jain's avatar
    cxl: Prevent adapter reset if an active context exists · 70b565bb
    Vaibhav Jain authored
    This patch prevents resetting the cxl adapter via sysfs in presence of
    one or more active cxl_context on it. This protects against an
    unrecoverable error caused by PSL owning a dirty cache line even after
    reset and host tries to touch the same cache line. In case a force reset
    of the card is required irrespective of any active contexts, the int
    value -1 can be stored in the 'reset' sysfs attribute of the card.
    The patch introduces a new atomic_t member named contexts_num inside
    struct cxl that holds the number of active context attached to the card
    , which is checked against '0' before proceeding with the reset. To
    prevent against a race condition where a context is activated just after
    reset check is performed, the contexts_num is atomically set to '-1'
    after reset-check to indicate that no more contexts can be activated on
    the card anymore.
    Before activating a context we atomically test if contexts_num is
    non-negative and if so, increment its value by one. In case the value of
    contexts_num is negative then it indicates that the card is about to be
    reset and context activation is error-ed out at that point.
    Fixes: 62fa19d4 ("cxl: Add ability to reset the card")
    Cc: stable@vger.kernel.org # v4.0+
    Acked-by: default avatarFrederic Barrat <fbarrat@linux.vnet.ibm.com>
    Reviewed-by: default avatarAndrew Donnellan <andrew.donnellan@au1.ibm.com>
    Signed-off-by: default avatarVaibhav Jain <vaibhav@linux.vnet.ibm.com>
    Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
sysfs.c 18 KB