[PATCH 02/10] drm: drm_printer: Add printer for devcoredump

[Jordan Crouse]

Add a drm printer suitable for use with the read callback for
devcoredump or any other file operation read() function that
isn't otherwise covered by seq_file.

Signed-off-by: Jordan Crouse 
---
 drivers/gpu/drm/drm_print.c | 54 +
 include/drm/drm_print.h | 27 +++
 2 files changed, 81 insertions(+)

diff --git a/drivers/gpu/drm/drm_print.c b/drivers/gpu/drm/drm_print.c
index 781518fd88e3..f6efde48f8b3 100644
--- a/drivers/gpu/drm/drm_print.c
+++ b/drivers/gpu/drm/drm_print.c
@@ -30,6 +30,60 @@
 #include 
 #include 
 
+void __drm_printfn_coredump(struct drm_printer *p, struct va_format *vaf)
+{
+   struct drm_print_iterator *iterator = p->arg;
+
+   ssize_t len;
+
+   if (!iterator->remain)
+   return;
+
+   if (iterator->offset < iterator->start) {
+   char *buf;
+   ssize_t copy;
+
+   /* Figure out how big the string will be */
+   len = snprintf(NULL, 0, "%pV", vaf);
+
+   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)
+   copy = iterator->remain;
+
+   /* Copy out the bit of the string that we need */
+   memcpy(iterator->data,
+   buf + (iterator->start - iterator->offset), copy);
+
+   iterator->offset = iterator->start + copy;
+   iterator->remain -= copy;
+
+   kfree(buf);
+   } else {
+   ssize_t pos = iterator->offset - iterator->start;
+
+   len = scnprintf(((char *) iterator->data) + pos,
+   iterator->remain, "%pV", vaf);
+
+   iterator->offset += len;
+   iterator->remain -= len;
+   }
+}
+EXPORT_SYMBOL(__drm_printfn_coredump);
+
 void __drm_printfn_seq_file(struct drm_printer *p, struct va_format *vaf)
 {
seq_printf(p->arg, "%pV", vaf);
diff --git a/include/drm/drm_print.h b/include/drm/drm_print.h
index 2a4a42e59a47..29eee5175eac 100644
--- a/include/drm/drm_print.h
+++ b/include/drm/drm_print.h
@@ -73,6 +73,7 @@ struct drm_printer {
const char *prefix;
 };
 
+void __drm_printfn_coredump(struct drm_printer *p, struct va_format *vaf);
 void __drm_printfn_seq_file(struct drm_printer *p, struct va_format *vaf);
 void __drm_printfn_info(struct drm_printer *p, struct va_format *vaf);
 void __drm_printfn_debug(struct drm_printer *p, struct va_format *vaf);
@@ -104,6 +105,32 @@ drm_vprintf(struct drm_printer *p, const char *fmt, 
va_list *va)
 #define drm_printf_indent(printer, indent, fmt, ...) \
drm_printf((printer), "%.*s" fmt, (indent), "\t\t\t\t\tX", 
##__VA_ARGS__)
 
+struct drm_print_iterator {
+   void *data;
+
+   ssize_t start;
+   ssize_t offset;
+   ssize_t remain;
+};
+
+/**
+ * drm_coredump_printer - construct a _printer that can output to a buffer
+ * from the read function for devcoredump
+ * @iter: A pointer to a struct drm_print_iterator for the read instance
+ *
+ * RETURNS:
+ * The _printer object
+ */
+static inline struct drm_printer
+drm_coredump_printer(struct drm_print_iterator *iter)
+{
+   struct drm_printer p = {
+   .printfn = __drm_printfn_coredump,
+   .arg = iter,
+   };
+   return p;
+}
+
 /**
  * drm_seq_file_printer - construct a _printer that outputs to _file
  * @f:  the  seq_file to output to
-- 
2.17.0

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Re: [PATCH 02/10] drm: drm_printer: Add printer for devcoredump

[Chris Wilson]

Quoting Chris Wilson (2018-04-06 11:42:25)
> Quoting Jordan Crouse (2018-04-05 23:00:48)
> > +struct drm_print_iterator {
> > +   void *data;
> > +
> > +   ssize_t start;
> > +   ssize_t offset;
> > +   ssize_t remain;
> > +};
> 
> Neat, we should be able to use to replace struct
> drm_i915_error_state_buf (or at least the seq_file side).

Though comparing against which, we have loff_t for that interface.
But that's immaterial for an in-memory file. (So nothing to see here,
please move along.)
-Chris
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Re: [PATCH 02/10] drm: drm_printer: Add printer for devcoredump

[Chris Wilson]

Quoting Jordan Crouse (2018-04-05 23:00:48)
> +struct drm_print_iterator {
> +   void *data;
> +
> +   ssize_t start;
> +   ssize_t offset;
> +   ssize_t remain;
> +};

Neat, we should be able to use to replace struct
drm_i915_error_state_buf (or at least the seq_file side).
-Chris
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[PATCH 02/10] drm: drm_printer: Add printer for devcoredump

[Jordan Crouse]

Add a drm printer suitable for use with the read callback for
devcoredump or any other file operation read() function that
isn't otherwise covered by seq_file.

Signed-off-by: Jordan Crouse 
---
 drivers/gpu/drm/drm_print.c | 54 +
 include/drm/drm_print.h | 27 +++
 2 files changed, 81 insertions(+)

diff --git a/drivers/gpu/drm/drm_print.c b/drivers/gpu/drm/drm_print.c
index 781518fd88e3..f6efde48f8b3 100644
--- a/drivers/gpu/drm/drm_print.c
+++ b/drivers/gpu/drm/drm_print.c
@@ -30,6 +30,60 @@
 #include 
 #include 
 
+void __drm_printfn_coredump(struct drm_printer *p, struct va_format *vaf)
+{
+   struct drm_print_iterator *iterator = p->arg;
+
+   ssize_t len;
+
+   if (!iterator->remain)
+   return;
+
+   if (iterator->offset < iterator->start) {
+   char *buf;
+   ssize_t copy;
+
+   /* Figure out how big the string will be */
+   len = snprintf(NULL, 0, "%pV", vaf);
+
+   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)
+   copy = iterator->remain;
+
+   /* Copy out the bit of the string that we need */
+   memcpy(iterator->data,
+   buf + (iterator->start - iterator->offset), copy);
+
+   iterator->offset = iterator->start + copy;
+   iterator->remain -= copy;
+
+   kfree(buf);
+   } else {
+   ssize_t pos = iterator->offset - iterator->start;
+
+   len = scnprintf(((char *) iterator->data) + pos,
+   iterator->remain, "%pV", vaf);
+
+   iterator->offset += len;
+   iterator->remain -= len;
+   }
+}
+EXPORT_SYMBOL(__drm_printfn_coredump);
+
 void __drm_printfn_seq_file(struct drm_printer *p, struct va_format *vaf)
 {
seq_printf(p->arg, "%pV", vaf);
diff --git a/include/drm/drm_print.h b/include/drm/drm_print.h
index 2a4a42e59a47..29eee5175eac 100644
--- a/include/drm/drm_print.h
+++ b/include/drm/drm_print.h
@@ -73,6 +73,7 @@ struct drm_printer {
const char *prefix;
 };
 
+void __drm_printfn_coredump(struct drm_printer *p, struct va_format *vaf);
 void __drm_printfn_seq_file(struct drm_printer *p, struct va_format *vaf);
 void __drm_printfn_info(struct drm_printer *p, struct va_format *vaf);
 void __drm_printfn_debug(struct drm_printer *p, struct va_format *vaf);
@@ -104,6 +105,32 @@ drm_vprintf(struct drm_printer *p, const char *fmt, 
va_list *va)
 #define drm_printf_indent(printer, indent, fmt, ...) \
drm_printf((printer), "%.*s" fmt, (indent), "\t\t\t\t\tX", 
##__VA_ARGS__)
 
+struct drm_print_iterator {
+   void *data;
+
+   ssize_t start;
+   ssize_t offset;
+   ssize_t remain;
+};
+
+/**
+ * drm_coredump_printer - construct a _printer that can output to a buffer
+ * from the read function for devcoredump
+ * @iter: A pointer to a struct drm_print_iterator for the read instance
+ *
+ * RETURNS:
+ * The _printer object
+ */
+static inline struct drm_printer
+drm_coredump_printer(struct drm_print_iterator *iter)
+{
+   struct drm_printer p = {
+   .printfn = __drm_printfn_coredump,
+   .arg = iter,
+   };
+   return p;
+}
+
 /**
  * drm_seq_file_printer - construct a _printer that outputs to _file
  * @f:  the  seq_file to output to
-- 
2.16.1

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