scftorture: Count single_rpc offline failures in statistics outputgrafted

scf_torture_stats_print() aggregates each invoker thread's counters
into a local scf_statistics structure before printing, but the
n_single_rpc_ofl field is missing from the aggregation loop.  As a
result, the "single_rpc_ofl" value printed in the statistics line is
always zero, even when smp_call_function_single() invocations for the
RPC test have failed due to offline CPUs and been counted by the
invoker threads.

Add the missing accumulation so that the printed value reflects the
actual counts.

Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

1 files changed, 105 insertions, 0 deletions

diff --git a/rust/macros/vtable.rs b/rust/macros/vtable.rs
new file mode 100644
index 000000000..c6510b0c4
--- /dev/null
+++ b/rust/macros/vtable.rs
@@ -0,0 +1,105 @@
+// SPDX-License-Identifier: GPL-2.0
+
+use std::{
+    collections::HashSet,
+    iter::Extend, //
+};
+
+use proc_macro2::{
+    Ident,
+    TokenStream, //
+};
+use quote::ToTokens;
+use syn::{
+    parse_quote,
+    Error,
+    ImplItem,
+    Item,
+    ItemImpl,
+    ItemTrait,
+    Result,
+    TraitItem, //
+};
+
+fn handle_trait(mut item: ItemTrait) -> Result<ItemTrait> {
+    let mut gen_items = Vec::new();
+
+    gen_items.push(parse_quote! {
+         /// A marker to prevent implementors from forgetting to use [`#[vtable]`](vtable)
+         /// attribute when implementing this trait.
+         const USE_VTABLE_ATTR: ();
+    });
+
+    for item in &item.items {
+        if let TraitItem::Fn(fn_item) = item {
+            let name = &fn_item.sig.ident;
+            let gen_const_name = Ident::new(
+                &format!("HAS_{}", name.to_string().to_uppercase()),
+                name.span(),
+            );
+
+            // We don't know on the implementation-site whether a method is required or provided
+            // so we have to generate a const for all methods.
+            let cfg_attrs = crate::helpers::gather_cfg_attrs(&fn_item.attrs);
+            let comment =
+                format!("Indicates if the `{name}` method is overridden by the implementor.");
+            gen_items.push(parse_quote! {
+                #(#cfg_attrs)*
+                #[doc = #comment]
+                const #gen_const_name: bool = false;
+            });
+        }
+    }
+
+    item.items.extend(gen_items);
+    Ok(item)
+}
+
+fn handle_impl(mut item: ItemImpl) -> Result<ItemImpl> {
+    let mut gen_items = Vec::new();
+    let mut defined_consts = HashSet::new();
+
+    // Iterate over all user-defined constants to gather any possible explicit overrides.
+    for item in &item.items {
+        if let ImplItem::Const(const_item) = item {
+            defined_consts.insert(const_item.ident.clone());
+        }
+    }
+
+    gen_items.push(parse_quote! {
+        const USE_VTABLE_ATTR: () = ();
+    });
+
+    for item in &item.items {
+        if let ImplItem::Fn(fn_item) = item {
+            let name = &fn_item.sig.ident;
+            let gen_const_name = Ident::new(
+                &format!("HAS_{}", name.to_string().to_uppercase()),
+                name.span(),
+            );
+            // Skip if it's declared already -- this allows user override.
+            if defined_consts.contains(&gen_const_name) {
+                continue;
+            }
+            let cfg_attrs = crate::helpers::gather_cfg_attrs(&fn_item.attrs);
+            gen_items.push(parse_quote! {
+                #(#cfg_attrs)*
+                const #gen_const_name: bool = true;
+            });
+        }
+    }
+
+    item.items.extend(gen_items);
+    Ok(item)
+}
+
+pub(crate) fn vtable(input: Item) -> Result<TokenStream> {
+    match input {
+        Item::Trait(item) => Ok(handle_trait(item)?.into_token_stream()),
+        Item::Impl(item) => Ok(handle_impl(item)?.into_token_stream()),
+        _ => Err(Error::new_spanned(
+            input,
+            "`#[vtable]` attribute should only be applied to trait or impl block",
+        ))?,
+    }
+}