drm: Add puts callback for the coredump printer

Add a puts function for the coredump printer to bypass printf()
for constant strings for a speed boost. Reorganize the
coredump printf callback to share as much code as possible.

v2: Try to reuse code between print and puts as suggested by
    Chris Wilson

Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>

diff --git a/drivers/gpu/drm/drm_print.c b/drivers/gpu/drm/drm_print.c
index 45d7876117239f96a6da4f9084d3da9315a55632..0e7fc3e7dfb48878671cbf709063e1489485186b 100644 (file)
--- a/drivers/gpu/drm/drm_print.c
+++ b/drivers/gpu/drm/drm_print.c
@@ -30,7 +30,7 @@
 #include <drm/drmP.h>
 #include <drm/drm_print.h>
 
-void __drm_printfn_coredump(struct drm_printer *p, struct va_format *vaf)
+void __drm_puts_coredump(struct drm_printer *p, const char *str)
 {
        struct drm_print_iterator *iterator = p->arg;
        ssize_t len;
@@ -38,26 +38,16 @@ void __drm_printfn_coredump(struct drm_printer *p, struct va_format *vaf)
        if (!iterator->remain)
                return;
 
-       /* Figure out how big the string will be */
-       len = snprintf(NULL, 0, "%pV", vaf);
-
        if (iterator->offset < iterator->start) {
-               char *buf;
                ssize_t copy;
 
+               len = strlen(str);
+
                if (iterator->offset + len <= iterator->start) {
                        iterator->offset += len;
                        return;
                }
 
-               /* Print the string into a temporary buffer */
-               buf = kmalloc(len + 1,
-                       GFP_KERNEL | __GFP_NOWARN | __GFP_NORETRY);
-               if (!buf)
-                       return;
-
-               snprintf(buf, len + 1, "%pV", vaf);
-
                copy = len - (iterator->start - iterator->offset);
 
                if (copy > iterator->remain)
@@ -65,42 +55,66 @@ void __drm_printfn_coredump(struct drm_printer *p, struct va_format *vaf)
 
                /* Copy out the bit of the string that we need */
                memcpy(iterator->data,
-                       buf + (iterator->start - iterator->offset), copy);
+                       str + (iterator->start - iterator->offset), copy);
 
                iterator->offset = iterator->start + copy;
                iterator->remain -= copy;
-
-               kfree(buf);
        } else {
-               char *buf;
                ssize_t pos = iterator->offset - iterator->start;
 
-               if (len < iterator->remain) {
-                       snprintf(((char *) iterator->data) + pos,
-                               iterator->remain, "%pV", vaf);
+               len = min_t(ssize_t, strlen(str), iterator->remain);
 
-                       iterator->offset += len;
-                       iterator->remain -= len;
+               memcpy(iterator->data + pos, str, len);
 
-                       return;
-               }
+               iterator->offset += len;
+               iterator->remain -= len;
+       }
+}
+EXPORT_SYMBOL(__drm_puts_coredump);
 
-               /* Print the string into a temporary buffer */
-               buf = kmalloc(len + 1,
-                       GFP_KERNEL | __GFP_NOWARN | __GFP_NORETRY);
-               if (!buf)
-                       return;
+void __drm_printfn_coredump(struct drm_printer *p, struct va_format *vaf)
+{
+       struct drm_print_iterator *iterator = p->arg;
+       size_t len;
+       char *buf;
+
+       if (!iterator->remain)
+               return;
+
+       /* Figure out how big the string will be */
+       len = snprintf(NULL, 0, "%pV", vaf);
+
+       /* This is the easiest path, we've already advanced beyond the offset */
+       if (iterator->offset + len <= iterator->start) {
+               iterator->offset += len;
+               return;
+       }
 
-               snprintf(buf, len + 1, "%pV", vaf);
+       /* Then check if we can directly copy into the target buffer */
+       if ((iterator->offset >= iterator->start) && (len < iterator->remain)) {
+               ssize_t pos = iterator->offset - iterator->start;
 
-               /* Copy out the remaining bits */
-               memcpy(iterator->data + pos, buf, iterator->remain);
+               snprintf(((char *) iterator->data) + pos,
+                       iterator->remain, "%pV", vaf);
 
-               iterator->offset += iterator->remain;
-               iterator->remain = 0;
+               iterator->offset += len;
+               iterator->remain -= len;
 
-               kfree(buf);
+               return;
        }
+
+       /*
+        * Finally, hit the slow path and make a temporary string to copy over
+        * using _drm_puts_coredump
+        */
+       buf = kmalloc(len + 1, GFP_KERNEL | __GFP_NOWARN | __GFP_NORETRY);
+       if (!buf)
+               return;
+
+       snprintf(buf, len + 1, "%pV", vaf);
+       __drm_puts_coredump(p, (const char *) buf);
+
+       kfree(buf);
 }
 EXPORT_SYMBOL(__drm_printfn_coredump);
 

diff --git a/include/drm/drm_print.h b/include/drm/drm_print.h
index b1432969b627b08a48acf3700955b1c6a3757f70..f3e6eed3e79c640e04ff1c163701a74a13ee9f40 100644 (file)
--- a/include/drm/drm_print.h
+++ b/include/drm/drm_print.h
@@ -75,6 +75,7 @@ struct drm_printer {
 };
 
 void __drm_printfn_coredump(struct drm_printer *p, struct va_format *vaf);
+void __drm_puts_coredump(struct drm_printer *p, const char *str);
 void __drm_printfn_seq_file(struct drm_printer *p, struct va_format *vaf);
 void __drm_puts_seq_file(struct drm_printer *p, const char *str);
 void __drm_printfn_info(struct drm_printer *p, struct va_format *vaf);
@@ -163,6 +164,7 @@ drm_coredump_printer(struct drm_print_iterator *iter)
 {
        struct drm_printer p = {
                .printfn = __drm_printfn_coredump,
+               .puts = __drm_puts_coredump,
                .arg = iter,
        };