From c4c493a4adcee75e1e44af044d0b7fc1b5192b61 Mon Sep 17 00:00:00 2001 From: Jason Wessel Date: Sun, 26 Aug 2012 22:37:03 -0500 Subject: kdb,vt_console: Fix missed data due to pager overruns commit 17b572e82032bc246324ce136696656b66d4e3f1 upstream. It is possible to miss data when using the kdb pager. The kdb pager does not pay attention to the maximum column constraint of the screen or serial terminal. This result is not incrementing the shown lines correctly and the pager will print more lines that fit on the screen. Obviously that is less than useful when using a VGA console where you cannot scroll back. The pager will now look at the kdb_buffer string to see how many characters are printed. It might not be perfect considering you can output ASCII that might move the cursor position, but it is a substantially better approximation for viewing dmesg and trace logs. This also means that the vt screen needs to set the kdb COLUMNS variable. Signed-off-by: Jason Wessel Signed-off-by: Greg Kroah-Hartman --- kernel/debug/kdb/kdb_io.c | 33 ++++++++++++++++++++++++++++----- 1 file changed, 28 insertions(+), 5 deletions(-) (limited to 'kernel') diff --git a/kernel/debug/kdb/kdb_io.c b/kernel/debug/kdb/kdb_io.c index bb9520f0f6f..572e604c562 100644 --- a/kernel/debug/kdb/kdb_io.c +++ b/kernel/debug/kdb/kdb_io.c @@ -552,6 +552,7 @@ int vkdb_printf(const char *fmt, va_list ap) { int diag; int linecount; + int colcount; int logging, saved_loglevel = 0; int saved_trap_printk; int got_printf_lock = 0; @@ -584,6 +585,10 @@ int vkdb_printf(const char *fmt, va_list ap) if (diag || linecount <= 1) linecount = 24; + diag = kdbgetintenv("COLUMNS", &colcount); + if (diag || colcount <= 1) + colcount = 80; + diag = kdbgetintenv("LOGGING", &logging); if (diag) logging = 0; @@ -690,7 +695,7 @@ kdb_printit: gdbstub_msg_write(kdb_buffer, retlen); } else { if (dbg_io_ops && !dbg_io_ops->is_console) { - len = strlen(kdb_buffer); + len = retlen; cp = kdb_buffer; while (len--) { dbg_io_ops->write_char(*cp); @@ -709,11 +714,29 @@ kdb_printit: printk(KERN_INFO "%s", kdb_buffer); } - if (KDB_STATE(PAGER) && strchr(kdb_buffer, '\n')) - kdb_nextline++; + if (KDB_STATE(PAGER)) { + /* + * Check printed string to decide how to bump the + * kdb_nextline to control when the more prompt should + * show up. + */ + int got = 0; + len = retlen; + while (len--) { + if (kdb_buffer[len] == '\n') { + kdb_nextline++; + got = 0; + } else if (kdb_buffer[len] == '\r') { + got = 0; + } else { + got++; + } + } + kdb_nextline += got / (colcount + 1); + } /* check for having reached the LINES number of printed lines */ - if (kdb_nextline == linecount) { + if (kdb_nextline >= linecount) { char buf1[16] = ""; #if defined(CONFIG_SMP) char buf2[32]; @@ -776,7 +799,7 @@ kdb_printit: kdb_grepping_flag = 0; kdb_printf("\n"); } else if (buf1[0] == ' ') { - kdb_printf("\n"); + kdb_printf("\r"); suspend_grep = 1; /* for this recursion */ } else if (buf1[0] == '\n') { kdb_nextline = linecount - 1; -- cgit v1.2.3-18-g5258