linux-kernel - [PATCH v3] lib/test_printf.c: accept "ptrval" as valid result for plain 'p' tests

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Date:   Wed, 13 Jun 2018 19:18:40 +0200
From:   Thierry Escande <thierry.escande@...aro.org>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        David Miller <davem@...emloft.net>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        Petr Mladek <pmladek@...e.com>
Cc:     Rasmus Villemoes <linux@...musvillemoes.dk>,
        "Tobin C . Harding" <me@...in.cc>, linux-kernel@...r.kernel.org
Subject: [PATCH v3] lib/test_printf.c: accept "ptrval" as valid result for plain 'p' tests

If the test_printf module is loaded before the crng is initialized, the
plain 'p' tests will fail because the printed address will not be hashed
and the buffer will contain "(____ptrval____)" or "(ptrval)" instead
(64-bit vs 32-bit).
Since we cannot wait for the crng to be initialized for an undefined
time, both plain 'p' tests now accept the strings "(____ptrval____)" or
"(ptrval)" as a valid result and print a warning message.

Signed-off-by: Thierry Escande <thierry.escande@...aro.org>
---

Changes in v3:
- Use "(____ptrval____)" for 64-bit
- Update commit message headline

Changes in v2:
- Remove wait_for_random_bytes() usage
- Remove Acked-by from Tobin as the proposed solution is not the same
  anymore.

 lib/test_printf.c | 24 ++++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/lib/test_printf.c b/lib/test_printf.c
index 71ebfa43ad05..31f00b8ca657 100644
--- a/lib/test_printf.c
+++ b/lib/test_printf.c
@@ -206,6 +206,7 @@ test_string(void)
 #define PTR_WIDTH 16
 #define PTR ((void *)0xffff0123456789ab)
 #define PTR_STR "ffff0123456789ab"
+#define PTR_VAL_NO_CRNG "(____ptrval____)"
 #define ZEROS "00000000"	/* hex 32 zero bits */
 
 static int __init
@@ -216,7 +217,16 @@ plain_format(void)
 
 	nchars = snprintf(buf, PLAIN_BUF_SIZE, "%p", PTR);
 
-	if (nchars != PTR_WIDTH || strncmp(buf, ZEROS, strlen(ZEROS)) != 0)
+	if (nchars != PTR_WIDTH)
+		return -1;
+
+	if (strncmp(buf, PTR_VAL_NO_CRNG, PTR_WIDTH) == 0) {
+		pr_warn("crng possibly not yet initialized. plain 'p' buffer contains \"%s\"",
+			PTR_VAL_NO_CRNG);
+		return 0;
+	}
+
+	if (strncmp(buf, ZEROS, strlen(ZEROS)) != 0)
 		return -1;
 
 	return 0;
@@ -227,6 +237,7 @@ plain_format(void)
 #define PTR_WIDTH 8
 #define PTR ((void *)0x456789ab)
 #define PTR_STR "456789ab"
+#define PTR_VAL_NO_CRNG "(ptrval)"
 
 static int __init
 plain_format(void)
@@ -245,7 +256,16 @@ plain_hash(void)
 
 	nchars = snprintf(buf, PLAIN_BUF_SIZE, "%p", PTR);
 
-	if (nchars != PTR_WIDTH || strncmp(buf, PTR_STR, PTR_WIDTH) == 0)
+	if (nchars != PTR_WIDTH)
+		return -1;
+
+	if (strncmp(buf, PTR_VAL_NO_CRNG, PTR_WIDTH) == 0) {
+		pr_warn("crng possibly not yet initialized. plain 'p' buffer contains \"%s\"",
+			PTR_VAL_NO_CRNG);
+		return 0;
+	}
+
+	if (strncmp(buf, PTR_STR, PTR_WIDTH) == 0)
 		return -1;
 
 	return 0;
-- 
2.14.1