[PATCH v3] staging: media: atomisp: refactor pipe graph dump stage formatting

[Neal Patalay]

The original implementation of ia_css_debug_pipe_graph_dump_stage()
includes an off-by-one error where the original strscpy() size dropped
characters immediately before newlines. It also allocates over 600
bytes across multiple buffers on the stack. Address these shortcomings
and reduce stack usage with a single 256 byte buffer via a new helper
function, ia_css_debug_build_info().

Fixes: 662fb4fceb1a ("media: atomisp: get rid of a string_support.h abstraction layer")
Signed-off-by: Neal Patalay <nealpatalay0@xxxxxxxxx>
---
v3:
- Moved "len_written" variable declaration to top of helper function
- Added local variables to track values inside helper function
- Fixed macro indentation
- Removed loop out of macro definition

v2:
- Fixed strscpy typo in commit message
- Changed Fixes tag to point to the actual buggy commit
- Dropped "flag" parameter from helper function and moved check to the macro
- Split long lines to conform with subsystem character limit
---
 .../pci/runtime/debug/src/ia_css_debug.c      | 185 +++++++-----------
 1 file changed, 70 insertions(+), 115 deletions(-)

diff --git a/drivers/staging/media/atomisp/pci/runtime/debug/src/ia_css_debug.c b/drivers/staging/media/atomisp/pci/runtime/debug/src/ia_css_debug.c
index 5113aa5973f3..e45334f7c2c4 100644
--- a/drivers/staging/media/atomisp/pci/runtime/debug/src/ia_css_debug.c
+++ b/drivers/staging/media/atomisp/pci/runtime/debug/src/ia_css_debug.c
@@ -1162,6 +1162,32 @@ void ia_css_debug_pipe_graph_dump_epilogue(void)
 	pg_inst.stream_format = N_ATOMISP_INPUT_FORMAT;
 }
 
+static void ia_css_debug_build_info(char *info, size_t info_size,
+				    int *offset,
+				    const char *flag_str, size_t flag_str_size,
+				    int *line_len)
+{
+	int len = *line_len;
+	int off = *offset;
+	int len_written;
+	/*
+	 * If new line length exceeds max line length,
+	 * replace the last ',' with a "\\n"
+	 */
+	if (len > 0 && info_size - off >= 2 &&
+	    len + flag_str_size > ENABLE_LINE_MAX_LENGTH) {
+		info[off - 1] = '\\';
+		info[off] = 'n';
+		off += 1;
+		len = 0;
+	}
+
+	len_written = scnprintf(info + off, info_size - off,
+				    "%s,", flag_str);
+	*offset = off + len_written;
+	*line_len = len + len_written;
+}
+
 void
 ia_css_debug_pipe_graph_dump_stage(
     struct ia_css_pipeline_stage *stage,
@@ -1194,123 +1220,52 @@ ia_css_debug_pipe_graph_dump_stage(
 
 	/* Guard in case of binaries that don't have any binary_info */
 	if (stage->binary_info) {
-		char enable_info1[100];
-		char enable_info2[100];
-		char enable_info3[100];
-		char enable_info[302];
+		char enable_info[256];
+		int offset = 0;
+		int line_len = 0;
 		struct ia_css_binary_info *bi = stage->binary_info;
 
-		/* Split it in 2 function-calls to keep the amount of
-		 * parameters per call "reasonable"
-		 */
-		snprintf(enable_info1, sizeof(enable_info1),
-			 "%s%s%s%s%s%s%s%s%s%s%s%s%s%s",
-			 bi->enable.reduced_pipe ?	"rp," : "",
-			 bi->enable.vf_veceven ?		"vfve," : "",
-			 bi->enable.dis ?		"dis," : "",
-			 bi->enable.dvs_envelope ?	"dvse," : "",
-			 bi->enable.uds ?		"uds," : "",
-			 bi->enable.dvs_6axis ?		"dvs6," : "",
-			 bi->enable.block_output ?	"bo," : "",
-			 bi->enable.ds ?			"ds," : "",
-			 bi->enable.bayer_fir_6db ?	"bf6," : "",
-			 bi->enable.raw_binning ?	"rawb," : "",
-			 bi->enable.continuous ?		"cont," : "",
-			 bi->enable.s3a ?		"s3a," : "",
-			 bi->enable.fpnr ?		"fpnr," : "",
-			 bi->enable.sc ?			"sc," : ""
-			);
-
-		snprintf(enable_info2, sizeof(enable_info2),
-			 "%s%s%s%s%s%s%s%s%s%s%s",
-			 bi->enable.macc ?		"macc," : "",
-			 bi->enable.output ?		"outp," : "",
-			 bi->enable.ref_frame ?		"reff," : "",
-			 bi->enable.tnr ?		"tnr," : "",
-			 bi->enable.xnr ?		"xnr," : "",
-			 bi->enable.params ?		"par," : "",
-			 bi->enable.ca_gdc ?		"cagdc," : "",
-			 bi->enable.isp_addresses ?	"ispa," : "",
-			 bi->enable.in_frame ?		"inf," : "",
-			 bi->enable.out_frame ?		"outf," : "",
-			 bi->enable.high_speed ?		"hs," : ""
-			);
-
-		/* And merge them into one string */
-		snprintf(enable_info, sizeof(enable_info), "%s%s",
-			 enable_info1, enable_info2);
-		{
-			int l, p;
-			char *ei = enable_info;
-
-			l = strlen(ei);
-
-			/* Replace last ',' with \0 if present */
-			if (l && enable_info[l - 1] == ',')
-				enable_info[--l] = '\0';
-
-			if (l > ENABLE_LINE_MAX_LENGTH) {
-				/* Too big for one line, find last comma */
-				p = ENABLE_LINE_MAX_LENGTH;
-				while (ei[p] != ',')
-					p--;
-				/* Last comma found, copy till that comma */
-				strscpy(enable_info1, ei, umin(p, sizeof(enable_info1)));
-
-				ei += p + 1;
-				l = strlen(ei);
-
-				if (l <= ENABLE_LINE_MAX_LENGTH) {
-					/* The 2nd line fits */
-					/* we cannot use ei as argument because
-					 * it is not guaranteed dword aligned
-					 */
-
-					strscpy(enable_info2, ei, umin(l, sizeof(enable_info2)));
-
-					snprintf(enable_info, sizeof(enable_info), "%s\\n%s",
-						 enable_info1, enable_info2);
-
-				} else {
-					/* 2nd line is still too long */
-					p = ENABLE_LINE_MAX_LENGTH;
-					while (ei[p] != ',')
-						p--;
-
-					strscpy(enable_info2, ei, umin(p, sizeof(enable_info2)));
-
-					ei += p + 1;
-					l = strlen(ei);
-
-					if (l <= ENABLE_LINE_MAX_LENGTH) {
-						/* The 3rd line fits */
-						/* we cannot use ei as argument because
-						* it is not guaranteed dword aligned
-						*/
-						strscpy(enable_info3, ei,
-							sizeof(enable_info3));
-						snprintf(enable_info, sizeof(enable_info),
-							 "%s\\n%s\\n%s",
-							 enable_info1, enable_info2,
-							 enable_info3);
-					} else {
-						/* 3rd line is still too long */
-						p = ENABLE_LINE_MAX_LENGTH;
-						while (ei[p] != ',')
-							p--;
-						strscpy(enable_info3, ei,
-							umin(p, sizeof(enable_info3)));
-						ei += p + 1;
-						strscpy(enable_info3, ei,
-							sizeof(enable_info3));
-						snprintf(enable_info, sizeof(enable_info),
-							 "%s\\n%s\\n%s",
-							 enable_info1, enable_info2,
-							 enable_info3);
-					}
-				}
-			}
-		}
+#define ADD_INFO(flag, flag_str)						\
+	if (bi->enable.flag)							\
+		ia_css_debug_build_info(enable_info, sizeof(enable_info),	\
+					&offset,				\
+					flag_str, sizeof(flag_str),		\
+					&line_len)
+
+		/* Build string in enable_info buffer */
+		ADD_INFO(reduced_pipe, "rp");
+		ADD_INFO(vf_veceven, "vfve");
+		ADD_INFO(dis, "dis");
+		ADD_INFO(dvs_envelope, "dvse");
+		ADD_INFO(uds, "uds");
+		ADD_INFO(dvs_6axis, "dvs6");
+		ADD_INFO(block_output, "bo");
+		ADD_INFO(ds, "ds");
+		ADD_INFO(bayer_fir_6db, "bf6");
+		ADD_INFO(raw_binning, "rawb");
+		ADD_INFO(continuous, "cont");
+		ADD_INFO(s3a, "s3a");
+		ADD_INFO(fpnr, "fpnr");
+		ADD_INFO(sc, "sc");
+		ADD_INFO(macc, "macc");
+		ADD_INFO(output, "outp");
+		ADD_INFO(ref_frame, "reff");
+		ADD_INFO(tnr, "tnr");
+		ADD_INFO(xnr, "xnr");
+		ADD_INFO(params, "par");
+		ADD_INFO(ca_gdc, "cagdc");
+		ADD_INFO(isp_addresses, "ispa");
+		ADD_INFO(in_frame, "inf");
+		ADD_INFO(out_frame, "outf");
+		ADD_INFO(high_speed, "hs");
+
+#undef ADD_INFO
+
+		/* Replace last ',' with '\0' */
+		if (offset > 0)
+			enable_info[offset - 1] = '\0';
+		else
+			enable_info[0] = '\0';
 
 		dtrace_dot("node [shape = circle, fixedsize=true, width=2.5, label=\"%s\\n%s\\n\\n%s\"]; \"%s(pipe%d)\"",
 			   bin_type, blob_name, enable_info, blob_name, id);
-- 
2.55.0