Add a drm printer suitable for use with the read callback for
devcoredump or other suitable buffer based output format that
isn't otherwise covered by seq_file.
v2: Add improved documentation per Daniel Vetter
Signed-off-by: Jordan Crouse <jcrouse@xxxxxxxxxxxxxx>
---
drivers/gpu/drm/drm_print.c | 74 +++++++++++++++++++++++++++++++++++++
include/drm/drm_print.h | 65 ++++++++++++++++++++++++++++++++
2 files changed, 139 insertions(+)
diff --git a/drivers/gpu/drm/drm_print.c b/drivers/gpu/drm/drm_print.c
index b25f98f33f6c..03d1f98e5ac7 100644
--- a/drivers/gpu/drm/drm_print.c
+++ b/drivers/gpu/drm/drm_print.c
@@ -30,6 +30,80 @@
#include <drm/drmP.h>
#include <drm/drm_print.h>
+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;
+
+ /* Figure out how big the string will be */
+ len = snprintf(NULL, 0, "%pV", vaf);
+
+ if (iterator->offset < iterator->start) {
+ char *buf;
+ ssize_t copy;
+
+ 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 {
+ char *buf;
+ ssize_t pos = iterator->offset - iterator->start;
+
+ if (len < iterator->remain) {
+ snprintf(((char *) iterator->data) + pos,
+ iterator->remain, "%pV", vaf);
+
+ iterator->offset += len;
+ iterator->remain -= 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 out the remaining bits */
+ memcpy(iterator->data + pos, buf, iterator->remain);
+
+ iterator->offset += iterator->remain;
+ iterator->remain = 0;
+
+ kfree(buf);
+ }
+}
+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 e1a46e9991cc..3213d2896e9c 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 +105,70 @@ 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 - local struct used with drm_printer_coredump
+ * @data: Pointer to the devcoredump output buffer
+ * @start: The offset within the buffer to start writing
+ * @remain: The number of bytes to write for this iteration
+ */
+struct drm_print_iterator {
+ void *data;
+ ssize_t start;
+ ssize_t remain;
+ /* private: */
+ ssize_t offset;
+};
+
+/**
+ * drm_coredump_printer - construct a &drm_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
+ *
+ * This wrapper extends drm_printf() to work with a dev_coredumpm() callback
+ * function. The passed in drm_print_iterator struct contains the buffer
+ * pointer, size and offset as passed in from devcoredump.
+ *
+ * For example::
+ *
+ * void coredump_read(char *buffer, loff_t offset, size_t count,
+ * void *data, size_t datalen)
+ * {
+ * struct drm_print_iterator iter;
+ * struct drm_printer p;
+ *
+ * iter.data = buffer;
+ * iter.start = offset;
+ * iter.remain = count;
+ *
+ * p = drm_coredump_printer(&iter);
+ *
+ * drm_printf(p, "foo=%d\n", foo);
+ * }
+ *
+ * void makecoredump(...)
+ * {
+ * ...
+ * dev_coredumpm(dev, THIS_MODULE, data, 0, GFP_KERNEL,
+ * coredump_read, ...)
+ * }
+ *
+ * RETURNS:
+ * The &drm_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,
+ };
+
+ /* Set the internal offset of the iterator to zero */
+ iter->offset = 0;
+
+ return p;
+}
+
/**
* drm_seq_file_printer - construct a &drm_printer that outputs to &seq_file
* @f: the &struct seq_file to output to
--
2.18.0
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