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Commit caf9eb6b authored by Dave Hansen's avatar Dave Hansen Committed by Ingo Molnar
Browse files

x86/pkeys/selftests: Avoid printf-in-signal deadlocks 



printf() and friends are unusable in signal handlers.  They deadlock.
The pkey selftest does not do any normal printing in signal handlers,
only extra debugging.  So, just print the format string so we get
*some* output when debugging.

Signed-off-by: default avatarDave Hansen <dave.hansen@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael Ellermen <mpe@ellerman.id.au>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ram Pai <linuxram@us.ibm.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20180509171344.C53FD2F3@viggo.jf.intel.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent a50093d6

tools/testing/selftests/x86/pkey-helpers.h

+8 −12
Original line number Original line Diff line number Diff line
@@ -26,30 +26,26 @@ static inline void sigsafe_printf(const char *format, ...) 
{

{

	va_list ap;

	va_list ap;





	va_start(ap, format);

	if (!dprint_in_signal) {

	if (!dprint_in_signal) {

		va_start(ap, format);

		vprintf(format, ap);

		vprintf(format, ap);

		va_end(ap);

	} else {

	} else {

		int ret;

		int ret;

		int len = vsnprintf(dprint_in_signal_buffer,

				    DPRINT_IN_SIGNAL_BUF_SIZE,

				    format, ap);

		/*

		/*

		 * len is amount that would have been printed,

		 * No printf() functions are signal-safe.

		 * but actual write is truncated at BUF_SIZE.

		 * They deadlock easily. Write the format

		 * string to get some output, even if

		 * incomplete.

		 */

		 */

		if (len > DPRINT_IN_SIGNAL_BUF_SIZE)

		ret = write(1, format, strlen(format));

			len = DPRINT_IN_SIGNAL_BUF_SIZE;

		ret = write(1, dprint_in_signal_buffer, len);

		if (ret < 0)

		if (ret < 0)

			abort();

			exit(1);

	}

	}

	va_end(ap);

}

}

#define dprintf_level(level, args...) do {	\

#define dprintf_level(level, args...) do {	\

	if (level <= DEBUG_LEVEL)		\

	if (level <= DEBUG_LEVEL)		\

		sigsafe_printf(args);		\

		sigsafe_printf(args);		\

	fflush(NULL);				\

} while (0)

} while (0)

#define dprintf0(args...) dprintf_level(0, args)

#define dprintf0(args...) dprintf_level(0, args)

#define dprintf1(args...) dprintf_level(1, args)

#define dprintf1(args...) dprintf_level(1, args)