#include "config.h"
#include "dbg.h"
-static char print_string[TIPC_PB_MAX_STR];
-static DEFINE_SPINLOCK(print_lock);
+/*
+ * TIPC pre-defines the following print buffers:
+ *
+ * TIPC_NULL : null buffer (i.e. print nowhere)
+ * TIPC_CONS : system console
+ * TIPC_LOG : TIPC log buffer
+ *
+ * Additional user-defined print buffers are also permitted.
+ */
-static struct print_buf null_buf = { NULL, 0, NULL, NULL };
+static struct print_buf null_buf = { NULL, 0, NULL, 0 };
struct print_buf *TIPC_NULL = &null_buf;
-static struct print_buf cons_buf = { NULL, 0, NULL, NULL };
+static struct print_buf cons_buf = { NULL, 0, NULL, 1 };
struct print_buf *TIPC_CONS = &cons_buf;
-static struct print_buf log_buf = { NULL, 0, NULL, NULL };
+static struct print_buf log_buf = { NULL, 0, NULL, 1 };
struct print_buf *TIPC_LOG = &log_buf;
+/*
+ * Locking policy when using print buffers.
+ *
+ * 1) tipc_printf() uses 'print_lock' to protect against concurrent access to
+ * 'print_string' when writing to a print buffer. This also protects against
+ * concurrent writes to the print buffer being written to.
+ *
+ * 2) tipc_dump() and tipc_log_XXX() leverage the aforementioned
+ * use of 'print_lock' to protect against all types of concurrent operations
+ * on their associated print buffer (not just write operations).
+ *
+ * Note: All routines of the form tipc_printbuf_XXX() are lock-free, and rely
+ * on the caller to prevent simultaneous use of the print buffer(s) being
+ * manipulated.
+ */
+
+static char print_string[TIPC_PB_MAX_STR];
+static DEFINE_SPINLOCK(print_lock);
+
#define FORMAT(PTR,LEN,FMT) \
{\
*(PTR + LEN) = '\0';\
}
-/*
- * Locking policy when using print buffers.
- *
- * The following routines use 'print_lock' for protection:
- * 1) tipc_printf() - to protect its print buffer(s) and 'print_string'
- * 2) TIPC_TEE() - to protect its print buffer(s)
- * 3) tipc_dump() - to protect its print buffer(s) and 'print_string'
- * 4) tipc_log_XXX() - to protect TIPC_LOG
- *
- * All routines of the form tipc_printbuf_XXX() rely on the caller to prevent
- * simultaneous use of the print buffer(s) being manipulated.
- */
-
/**
* tipc_printbuf_init - initialize print buffer to empty
* @pb: pointer to print buffer structure
* @raw: pointer to character array used by print buffer
* @size: size of character array
*
- * Makes the print buffer a null device that discards anything written to it
- * if the character array is too small (or absent).
+ * Note: If the character array is too small (or absent), the print buffer
+ * becomes a null device that discards anything written to it.
*/
void tipc_printbuf_init(struct print_buf *pb, char *raw, u32 size)
pb->buf = raw;
pb->crs = raw;
pb->size = size;
- pb->next = NULL;
+ pb->echo = 0;
if (size < TIPC_PB_MIN_SIZE) {
pb->buf = NULL;
void tipc_printbuf_reset(struct print_buf *pb)
{
- tipc_printbuf_init(pb, pb->buf, pb->size);
+ if (pb->buf != NULL) {
+ pb->crs = pb->buf;
+ pb->buf[0] = 0;
+ pb->buf[pb->size - 1] = ~0;
+ }
}
/**
strcpy(pb_to->buf, "*** PRINT BUFFER MOVE ERROR ***");
pb_to->buf[pb_to->size - 1] = ~0;
pb_to->crs = strchr(pb_to->buf, 0);
- pb_to->next = NULL;
return;
}
}
/**
- * tipc_printf - append formatted output to print buffer chain
- * @pb: pointer to chain of print buffers (may be NULL)
+ * tipc_printf - append formatted output to print buffer
+ * @pb: pointer to print buffer
* @fmt: formatted info to be printed
*/
int chars_to_add;
int chars_left;
char save_char;
- struct print_buf *pb_next;
spin_lock_bh(&print_lock);
+
FORMAT(print_string, chars_to_add, fmt);
if (chars_to_add >= TIPC_PB_MAX_STR)
strcpy(print_string, "*** PRINT BUFFER STRING TOO LONG ***");
- while (pb) {
- if (pb == TIPC_CONS)
- printk(print_string);
- else if (pb->buf) {
- chars_left = pb->buf + pb->size - pb->crs - 1;
- if (chars_to_add <= chars_left) {
- strcpy(pb->crs, print_string);
- pb->crs += chars_to_add;
- } else if (chars_to_add >= (pb->size - 1)) {
- strcpy(pb->buf, print_string + chars_to_add + 1
- - pb->size);
- pb->crs = pb->buf + pb->size - 1;
- } else {
- strcpy(pb->buf, print_string + chars_left);
- save_char = print_string[chars_left];
- print_string[chars_left] = 0;
- strcpy(pb->crs, print_string);
- print_string[chars_left] = save_char;
- pb->crs = pb->buf + chars_to_add - chars_left;
- }
+ if (pb->buf) {
+ chars_left = pb->buf + pb->size - pb->crs - 1;
+ if (chars_to_add <= chars_left) {
+ strcpy(pb->crs, print_string);
+ pb->crs += chars_to_add;
+ } else if (chars_to_add >= (pb->size - 1)) {
+ strcpy(pb->buf, print_string + chars_to_add + 1
+ - pb->size);
+ pb->crs = pb->buf + pb->size - 1;
+ } else {
+ strcpy(pb->buf, print_string + chars_left);
+ save_char = print_string[chars_left];
+ print_string[chars_left] = 0;
+ strcpy(pb->crs, print_string);
+ print_string[chars_left] = save_char;
+ pb->crs = pb->buf + chars_to_add - chars_left;
}
- pb_next = pb->next;
- pb->next = NULL;
- pb = pb_next;
}
- spin_unlock_bh(&print_lock);
-}
-/**
- * TIPC_TEE - perform next output operation on both print buffers
- * @b0: pointer to chain of print buffers (may be NULL)
- * @b1: pointer to print buffer to add to chain
- *
- * Returns pointer to print buffer chain.
- */
-
-struct print_buf *TIPC_TEE(struct print_buf *b0, struct print_buf *b1)
-{
- struct print_buf *pb = b0;
+ if (pb->echo)
+ printk(print_string);
- if (!b0 || (b0 == b1))
- return b1;
-
- spin_lock_bh(&print_lock);
- while (pb->next) {
- if ((pb->next == b1) || (pb->next == b0))
- pb->next = pb->next->next;
- else
- pb = pb->next;
- }
- pb->next = b1;
spin_unlock_bh(&print_lock);
- return b0;
}
/**
}
/**
- * tipc_dump - dump non-console print buffer(s) to console
- * @pb: pointer to chain of print buffers
+ * tipc_dump - dump (non-console) print buffer to console
+ * @pb: pointer to print buffer
*/
void tipc_dump(struct print_buf *pb, const char *fmt, ...)
{
- struct print_buf *pb_next;
int len;
+ if (pb == TIPC_CONS)
+ return;
+
spin_lock_bh(&print_lock);
+
FORMAT(print_string, len, fmt);
printk(print_string);
- for (; pb; pb = pb->next) {
- if (pb != TIPC_CONS) {
- printk("\n---- Start of %s log dump ----\n\n",
- (pb == TIPC_LOG) ? "global" : "local");
- printbuf_dump(pb);
- tipc_printbuf_reset(pb);
- printk("\n---- End of dump ----\n");
- }
- pb_next = pb->next;
- pb->next = NULL;
- pb = pb_next;
- }
+ printk("\n---- Start of %s log dump ----\n\n",
+ (pb == TIPC_LOG) ? "global" : "local");
+ printbuf_dump(pb);
+ tipc_printbuf_reset(pb);
+ printk("\n---- End of dump ----\n");
+
spin_unlock_bh(&print_lock);
}
if (log_size) {
if (log_size < TIPC_PB_MIN_SIZE)
log_size = TIPC_PB_MIN_SIZE;
+ res = TIPC_LOG->echo;
tipc_printbuf_init(TIPC_LOG, kmalloc(log_size, GFP_ATOMIC),
log_size);
+ TIPC_LOG->echo = res;
res = !TIPC_LOG->buf;
}
spin_unlock_bh(&print_lock);
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