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Re: [Xen-devel] [PATCH v3 07/23] xsplice: Implement support for applying/reverting/replacing patches. (v5)



On 02/12/2016 06:05 PM, Konrad Rzeszutek Wilk wrote:
snip
+static void xsplice_do_single(unsigned int total_cpus)
+{
+    nmi_callback_t saved_nmi_callback;
+    struct payload *data, *tmp;
+    s_time_t timeout;
+    int rc;
+
+    data = xsplice_work.data;
+    timeout = xsplice_work.timeout + NOW();
+    if ( xsplice_do_wait(&xsplice_work.semaphore, timeout, total_cpus,
+                         "Timed out on CPU semaphore") )
+        return;
+
+    /* "Mask" NMIs. */
+    saved_nmi_callback = set_nmi_callback(mask_nmi_callback);
+
+    /* All CPUs are waiting, now signal to disable IRQs. */
+    xsplice_work.ready = 1;
+    smp_wmb();
+
+    atomic_inc(&xsplice_work.irq_semaphore);
+    if ( xsplice_do_wait(&xsplice_work.irq_semaphore, timeout, total_cpus,
+                         "Timed out on IRQ semaphore.") )
+        return;
+
+    local_irq_disable();
+    /* Now this function should be the only one on any stack.
+     * No need to lock the payload list or applied list. */
+    switch ( xsplice_work.cmd )
+    {
+    case XSPLICE_ACTION_APPLY:
+        rc = apply_payload(data);
+        if ( rc == 0 )
+            data->state = XSPLICE_STATE_APPLIED;
+        break;
+    case XSPLICE_ACTION_REVERT:
+        rc = revert_payload(data);
+        if ( rc == 0 )
+            data->state = XSPLICE_STATE_CHECKED;
+        break;
+    case XSPLICE_ACTION_REPLACE:
+        list_for_each_entry_safe_reverse ( data, tmp, &applied_list, list )
+        {
+            data->rc = revert_payload(data);
+            if ( data->rc == 0 )
+                data->state = XSPLICE_STATE_CHECKED;
+            else
+            {
+                rc = -EINVAL;
+                break;
+            }
+        }

You're using data as a loop iterator here but the variable serves another purpose outside the loop. That's not gonna end well.

--
Ross Lagerwall

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