Minimize ztest stack frame size

To ensure ztest behaves as similarly as possible to the kernel
implementation of ZFS we attempt to honor the kernel stack limits.
This includes keeping the individual stack frame sizes under 1K
in size.  We currently use gcc to detect and enforce this limit.

Therefore to get this building cleanly with full debugging enabled
the stack usage in the following functions has been reduced by
moving the buffer to the heap.

Signed-off-by: Brian Behlendorf <[email protected]>

1 files changed, 13 insertions, 4 deletions

diff --git a/cmd/ztest/ztest.c b/cmd/ztest/ztest.c
index 973e7b2f6..65cbbe0b4 100644
--- a/cmd/ztest/ztest.c
+++ b/cmd/ztest/ztest.c
@@ -5900,12 +5900,13 @@ exec_child(char *cmd, char *libpath, boolean_t ignorekill, int *statusp)
 {
 	pid_t pid;
 	int status;
-	char cmdbuf[MAXPATHLEN];
+	char *cmdbuf = NULL;
 
 	pid = fork();
 
 	if (cmd == NULL) {
-		(void) strlcpy(cmdbuf, getexecname(), sizeof (cmdbuf));
+		cmdbuf = umem_alloc(MAXPATHLEN, UMEM_NOFAIL);
+		(void) strlcpy(cmdbuf, getexecname(), MAXPATHLEN);
 		cmd = cmdbuf;
 	}
 
@@ -5931,6 +5932,11 @@ exec_child(char *cmd, char *libpath, boolean_t ignorekill, int *statusp)
 		fatal(B_TRUE, "exec failed: %s", cmd);
 	}
 
+	if (cmdbuf != NULL) {
+		umem_free(cmdbuf, MAXPATHLEN);
+		cmd = NULL;
+	}
+
 	while (waitpid(pid, &status, 0) != pid)
 		continue;
 	if (statusp != NULL)
@@ -5997,7 +6003,7 @@ main(int argc, char **argv)
 	char timebuf[100];
 	char numbuf[6];
 	spa_t *spa;
-	char cmd[MAXNAMELEN];
+	char *cmd;
 	boolean_t hasalt;
 	int f;
 	char *fd_data_str = getenv("ZTEST_FD_DATA");
@@ -6054,7 +6060,8 @@ main(int argc, char **argv)
 		    (u_longlong_t)ztest_opts.zo_time);
 	}
 
-	(void) strlcpy(cmd, getexecname(), sizeof (cmd));
+	cmd = umem_alloc(MAXNAMELEN, UMEM_NOFAIL);
+	(void) strlcpy(cmd, getexecname(), MAXNAMELEN);
 
 	zs->zs_do_init = B_TRUE;
 	if (strlen(ztest_opts.zo_alt_ztest) != 0) {
@@ -6195,5 +6202,7 @@ main(int argc, char **argv)
 		    kills, iters - kills, (100.0 * kills) / MAX(1, iters));
 	}
 
+	umem_free(cmd, MAXNAMELEN);
+
 	return (0);
 }