[PATCH] coccinelle: api: add kvmalloc script

[Denis Efremov]

Suggest kvmalloc instead of opencoded kmalloc && vmalloc condition.

Signed-off-by: Denis Efremov <efremov@xxxxxxxxx>
---

If coccinelle fails with "Segmentation fault" during analysis, then
one needs to increase stack limit, e.g. ulimit -s 32767.

Current, I've sent only one patch for this rule and will send the rest
after the merge window. https://lkml.org/lkml/2020/7/31/986

 scripts/coccinelle/api/kvmalloc.cocci | 127 ++++++++++++++++++++++++++
 1 file changed, 127 insertions(+)
 create mode 100644 scripts/coccinelle/api/kvmalloc.cocci

diff --git a/scripts/coccinelle/api/kvmalloc.cocci b/scripts/coccinelle/api/kvmalloc.cocci
new file mode 100644
index 000000000000..76d6aeab7c09
--- /dev/null
+++ b/scripts/coccinelle/api/kvmalloc.cocci
@@ -0,0 +1,127 @@
+// SPDX-License-Identifier: GPL-2.0-only
+///
+/// Find conditions in code for kmalloc/vmalloc calls.
+/// Suggest to use kvmalloc instead.
+///
+// Confidence: High
+// Copyright: (C) 2020 Denis Efremov ISPRAS
+// Options: --no-includes --include-headers
+//
+
+virtual patch
+virtual report
+virtual org
+virtual context
+
+@opportunity depends on !patch@
+expression E, E1, size;
+position p;
+@@
+
+(
+* if (\(size <= E1\|size < E1\|size == E1\|size > E1\) || ...)@p {
+    ...
+*    E = \(kmalloc\|kzalloc\|kcalloc\|kmalloc_node\|kzalloc_node\|
+*          kmalloc_array\|kmalloc_array_node\|kcalloc_node\)(..., size, ...)
+    ...
+  } else {
+    ...
+*    E = \(vmalloc\|vzalloc\|vmalloc_node\|vzalloc_node\)(..., size, ...)
+    ...
+  }
+|
+* E = \(kmalloc\|kzalloc\|kcalloc\|kmalloc_node\|kzalloc_node\|
+*       kmalloc_array\|kmalloc_array_node\|kcalloc_node\)(..., size, ...)
+  ... when != E = E1
+      when != size = E1
+      when any
+* if (\(!E\|E == NULL\))@p {
+    ...
+*   E = \(vmalloc\|vzalloc\|vmalloc_node\|vzalloc_node\)(..., size, ...)
+    ...
+  }
+)
+
+@depends on patch@
+expression E, E1, flags, size, node;
+identifier x;
+type T;
+@@
+
+(
+- if (\(size <= E1\|size < E1\|size == E1\|size > E1\))
+-    E = kmalloc(size, flags);
+- else
+-    E = vmalloc(size);
++ E = kvmalloc(size, flags);
+|
+- E = kmalloc(size, flags | __GFP_NOWARN);
+- if (\(!E\|E == NULL\))
+-   E = vmalloc(size);
++ E = kvmalloc(size, flags);
+|
+- T x = kmalloc(size, flags | __GFP_NOWARN);
+- if (\(!x\|x == NULL\))
+-   x = vmalloc(size);
++ T x = kvmalloc(size, flags);
+|
+- if (\(size <= E1\|size < E1\|size == E1\|size > E1\))
+-    E = kzalloc(size, flags);
+- else
+-    E = vzalloc(size);
++ E = kvzalloc(size, flags);
+|
+- E = kzalloc(size, flags | __GFP_NOWARN);
+- if (\(!E\|E == NULL\))
+-   E = vzalloc(size);
++ E = kvzalloc(size, flags);
+|
+- T x = kzalloc(size, flags | __GFP_NOWARN);
+- if (\(!x\|x == NULL\))
+-   x = vzalloc(size);
++ T x = kvzalloc(size, flags);
+|
+- if (\(size <= E1\|size < E1\|size == E1\|size > E1\))
+-    E = kmalloc_node(size, flags, node);
+- else
+-    E = vmalloc_node(size, node);
++ E = kvmalloc_node(size, flags, node);
+|
+- E = kmalloc_node(size, flags | __GFP_NOWARN, node);
+- if (\(!E\|E == NULL\))
+-   E = vmalloc_node(size, node);
++ E = kvmalloc_node(size, flags, node);
+|
+- T x = kmalloc_node(size, flags | __GFP_NOWARN, node);
+- if (\(!x\|x == NULL\))
+-   x = vmalloc_node(size, node);
++ T x = kvmalloc_node(size, flags, node);
+|
+- if (\(size <= E1\|size < E1\|size == E1\|size > E1\))
+-    E = kvzalloc_node(size, flags, node);
+- else
+-    E = vzalloc_node(size, node);
++ E = kvzalloc_node(size, flags, node);
+|
+- E = kvzalloc_node(size, flags | __GFP_NOWARN, node);
+- if (\(!E\|E == NULL\))
+-   E = vzalloc_node(size, node);
++ E = kvzalloc_node(size, flags, node);
+|
+- T x = kvzalloc_node(size, flags | __GFP_NOWARN, node);
+- if (\(!x\|x == NULL\))
+-   x = vzalloc_node(size, node);
++ T x = kvzalloc_node(size, flags, node);
+)
+
+@script: python depends on report@
+p << opportunity.p;
+@@
+
+coccilib.report.print_report(p[0], "WARNING: opportunity for kvmalloc")
+
+@script: python depends on org@
+p << opportunity.p;
+@@
+
+coccilib.org.print_todo(p[0], "WARNING: opportunity for kvmalloc")
-- 
2.26.2