diff --git a/net/tipc/core.h b/net/tipc/core.h index 325404fd4eb..7042ef37726 100644 --- a/net/tipc/core.h +++ b/net/tipc/core.h @@ -66,7 +66,6 @@ struct tipc_msg; extern struct print_buf *TIPC_NULL, *TIPC_CONS, *TIPC_LOG; -extern struct print_buf *TIPC_TEE(struct print_buf *, struct print_buf *); void tipc_msg_print(struct print_buf*,struct tipc_msg *,const char*); void tipc_printf(struct print_buf *, const char *fmt, ...); void tipc_dump(struct print_buf*,const char *fmt, ...); @@ -98,11 +97,13 @@ void tipc_dump(struct print_buf*,const char *fmt, ...); * TIPC_CONS : system console * TIPC_LOG : TIPC log buffer * &buf : user-defined buffer (struct print_buf *) - * TIPC_TEE(&buf_a,&buf_b) : list of buffers (eg. TIPC_TEE(TIPC_CONS,TIPC_LOG)) + * + * Note: TIPC_LOG is configured to echo its output to the system console; + * user-defined buffers can be configured to do the same thing. */ #ifndef TIPC_OUTPUT -#define TIPC_OUTPUT TIPC_TEE(TIPC_CONS,TIPC_LOG) +#define TIPC_OUTPUT TIPC_LOG #endif #ifndef DBG_OUTPUT diff --git a/net/tipc/dbg.c b/net/tipc/dbg.c index 834319e3b7e..8ca9457250b 100644 --- a/net/tipc/dbg.c +++ b/net/tipc/dbg.c @@ -38,18 +38,44 @@ #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) \ {\ @@ -60,27 +86,14 @@ struct print_buf *TIPC_LOG = &log_buf; *(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) @@ -88,7 +101,7 @@ 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; @@ -105,7 +118,11 @@ void tipc_printbuf_init(struct print_buf *pb, char *raw, u32 size) 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; + } } /** @@ -182,7 +199,6 @@ void tipc_printbuf_move(struct print_buf *pb_to, struct print_buf *pb_from) 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; } @@ -205,8 +221,8 @@ void tipc_printbuf_move(struct print_buf *pb_to, struct print_buf *pb_from) } /** - * 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 */ @@ -215,68 +231,38 @@ void tipc_printf(struct print_buf *pb, const char *fmt, ...) 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; } + + if (pb->echo) + printk(print_string); + 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 (!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; -} - /** * print_to_console - write string of bytes to console in multiple chunks */ @@ -323,31 +309,28 @@ static void printbuf_dump(struct print_buf *pb) } /** - * 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); } @@ -368,8 +351,10 @@ int tipc_log_resize(int log_size) 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); diff --git a/net/tipc/dbg.h b/net/tipc/dbg.h index 6b00062bf04..5ef1bc8f64e 100644 --- a/net/tipc/dbg.h +++ b/net/tipc/dbg.h @@ -42,14 +42,14 @@ * @buf: pointer to character array containing print buffer contents * @size: size of character array * @crs: pointer to first unused space in character array (i.e. final NUL) - * @next: used to link print buffers when printing to more than one at a time + * @echo: echo output to system console if non-zero */ struct print_buf { char *buf; u32 size; char *crs; - struct print_buf *next; + int echo; }; #define TIPC_PB_MIN_SIZE 64 /* minimum size for a print buffer's array */