[PATCH 21.11] test/mbuf: fix crash in a forked process

[PATCH 21.11] test/mbuf: fix crash in a forked process

[Ruifeng Wang]

[ upstream commit b6c419dde10e9f5dec7a02098c48060a7493420c ]

test/mbuf: fix crash in a forked process

Access of any memory in the hugepage shared file-backed area will trigger
an unexpected forked child process segment fault. The root cause is DPDK
doesn't support fork model [1] (calling rte_eal_init() before fork()).
Forked child process can't be treated as a secondary process.

Hence fix it by avoiding fork and doing verification in the main process.

[1] https://mails.dpdk.org/archives/dev/2018-July/108106.html

Fixes: af75078fece3 ("first public release")

Signed-off-by: Jia He <justin.he@arm.com>
Signed-off-by: Ruifeng Wang <ruifeng.wang@arm.com>
Acked-by: Anatoly Burakov <anatoly.burakov@intel.com>
---
 app/test/test_mbuf.c | 49 +++++++++++++-------------------------------
 1 file changed, 14 insertions(+), 35 deletions(-)

diff --git a/app/test/test_mbuf.c b/app/test/test_mbuf.c
index 2287bce2f9..9c0ac63f92 100644
--- a/app/test/test_mbuf.c
+++ b/app/test/test_mbuf.c
@@ -1172,37 +1172,16 @@ test_refcnt_mbuf(void)
 #endif
 }
 
-#include <unistd.h>
-#include <sys/resource.h>
-#include <sys/time.h>
-#include <sys/wait.h>
-
-/* use fork() to test mbuf errors panic */
-static int
-verify_mbuf_check_panics(struct rte_mbuf *buf)
+/* Verify if mbuf can pass the check */
+static bool
+mbuf_check_pass(struct rte_mbuf *buf)
 {
-	int pid;
-	int status;
-
-	pid = fork();
-
-	if (pid == 0) {
-		struct rlimit rl;
+	const char *reason;
 
-		/* No need to generate a coredump when panicking. */
-		rl.rlim_cur = rl.rlim_max = 0;
-		setrlimit(RLIMIT_CORE, &rl);
-		rte_mbuf_sanity_check(buf, 1); /* should panic */
-		exit(0);  /* return normally if it doesn't panic */
-	} else if (pid < 0) {
-		printf("Fork Failed\n");
-		return -1;
-	}
-	wait(&status);
-	if(status == 0)
-		return -1;
+	if (rte_mbuf_check(buf, 1, &reason) == 0)
+		return true;
 
-	return 0;
+	return false;
 }
 
 static int
@@ -1219,47 +1198,47 @@ test_failing_mbuf_sanity_check(struct rte_mempool *pktmbuf_pool)
 		return -1;
 
 	printf("Checking good mbuf initially\n");
-	if (verify_mbuf_check_panics(buf) != -1)
+	if (!mbuf_check_pass(buf))
 		return -1;
 
 	printf("Now checking for error conditions\n");
 
-	if (verify_mbuf_check_panics(NULL)) {
+	if (mbuf_check_pass(NULL)) {
 		printf("Error with NULL mbuf test\n");
 		return -1;
 	}
 
 	badbuf = *buf;
 	badbuf.pool = NULL;
-	if (verify_mbuf_check_panics(&badbuf)) {
+	if (mbuf_check_pass(&badbuf)) {
 		printf("Error with bad-pool mbuf test\n");
 		return -1;
 	}
 
 	badbuf = *buf;
 	badbuf.buf_iova = 0;
-	if (verify_mbuf_check_panics(&badbuf)) {
+	if (mbuf_check_pass(&badbuf)) {
 		printf("Error with bad-physaddr mbuf test\n");
 		return -1;
 	}
 
 	badbuf = *buf;
 	badbuf.buf_addr = NULL;
-	if (verify_mbuf_check_panics(&badbuf)) {
+	if (mbuf_check_pass(&badbuf)) {
 		printf("Error with bad-addr mbuf test\n");
 		return -1;
 	}
 
 	badbuf = *buf;
 	badbuf.refcnt = 0;
-	if (verify_mbuf_check_panics(&badbuf)) {
+	if (mbuf_check_pass(&badbuf)) {
 		printf("Error with bad-refcnt(0) mbuf test\n");
 		return -1;
 	}
 
 	badbuf = *buf;
 	badbuf.refcnt = UINT16_MAX;
-	if (verify_mbuf_check_panics(&badbuf)) {
+	if (mbuf_check_pass(&badbuf)) {
 		printf("Error with bad-refcnt(MAX) mbuf test\n");
 		return -1;
 	}
-- 
2.25.1

Re: [PATCH 21.11] test/mbuf: fix crash in a forked process

[Kevin Traynor]

On 25/07/2023 09:53, Ruifeng Wang wrote:
> [ upstream commit b6c419dde10e9f5dec7a02098c48060a7493420c ]
> 
> test/mbuf: fix crash in a forked process
> 
> Access of any memory in the hugepage shared file-backed area will trigger
> an unexpected forked child process segment fault. The root cause is DPDK
> doesn't support fork model [1] (calling rte_eal_init() before fork()).
> Forked child process can't be treated as a secondary process.
> 
> Hence fix it by avoiding fork and doing verification in the main process.
> 
> [1]https://mails.dpdk.org/archives/dev/2018-July/108106.html
> 
> Fixes: af75078fece3 ("first public release")
> 
> Signed-off-by: Jia He<justin.he@arm.com>
> Signed-off-by: Ruifeng Wang<ruifeng.wang@arm.com>
> Acked-by: Anatoly Burakov<anatoly.burakov@intel.com>
> ---

Thanks for the backport. Queued, and will push to 21.11 dpdk.org branch 
in coming days.