Merge branch 'core/mutexes' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip into drm-next

Merge in the tip core/mutexes branch for future GPU driver use.

Ingo will send this branch to Linus prior to drm-next.

* 'core/mutexes' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits)
  locking-selftests: Handle unexpected failures more strictly
  mutex: Add more w/w tests to test EDEADLK path handling
  mutex: Add more tests to lib/locking-selftest.c
  mutex: Add w/w tests to lib/locking-selftest.c
  mutex: Add w/w mutex slowpath debugging
  mutex: Add support for wound/wait style locks
  arch: Make __mutex_fastpath_lock_retval return whether fastpath succeeded or not
  powerpc/pci: Fix boot panic on mpc83xx (regression)
  s390/ipl: Fix FCP WWPN and LUN format strings for read
  fs: fix new splice.c kernel-doc warning
  spi/pxa2xx: fix memory corruption due to wrong size used in devm_kzalloc()
  s390/mem_detect: fix memory hole handling
  s390/dma: support debug_dma_mapping_error
  s390/dma: fix mapping_error detection
  s390/irq: Only define synchronize_irq() on SMP
  Input: xpad - fix for "Mad Catz Street Fighter IV FightPad" controllers
  Input: wacom - add a new stylus (0x100802) for Intuos5 and Cintiqs
  spi/pxa2xx: use GFP_ATOMIC in sg table allocation
  fuse: hold i_mutex in fuse_file_fallocate()
  Input: add missing dependencies on CONFIG_HAS_IOMEM
  ...

arch/ia64/include/asm/mutex.h

@@ -29,17 +29,15 @@ __mutex_fastpath_lock(atomic_t *count, void (*fail_fn)(atomic_t *))
  *  __mutex_fastpath_lock_retval - try to take the lock by moving the count
  *                                 from 1 to a 0 value
  *  @count: pointer of type atomic_t
- *  @fail_fn: function to call if the original value was not 1
  *
- * Change the count from 1 to a value lower than 1, and call <fail_fn> if
- * it wasn't 1 originally. This function returns 0 if the fastpath succeeds,
- * or anything the slow path function returns.
+ * Change the count from 1 to a value lower than 1. This function returns 0
+ * if the fastpath succeeds, or -1 otherwise.
  */
 static inline int
-__mutex_fastpath_lock_retval(atomic_t *count, int (*fail_fn)(atomic_t *))
+__mutex_fastpath_lock_retval(atomic_t *count)
 {
 	if (unlikely(ia64_fetchadd4_acq(count, -1) != 1))
-		return fail_fn(count);
+		return -1;
 	return 0;
 }
 

arch/powerpc/include/asm/mutex.h

@@ -82,17 +82,15 @@ __mutex_fastpath_lock(atomic_t *count, void (*fail_fn)(atomic_t *))
  *  __mutex_fastpath_lock_retval - try to take the lock by moving the count
  *                                 from 1 to a 0 value
  *  @count: pointer of type atomic_t
- *  @fail_fn: function to call if the original value was not 1
  *
- * Change the count from 1 to a value lower than 1, and call <fail_fn> if
- * it wasn't 1 originally. This function returns 0 if the fastpath succeeds,
- * or anything the slow path function returns.
+ * Change the count from 1 to a value lower than 1. This function returns 0
+ * if the fastpath succeeds, or -1 otherwise.
  */
 static inline int
-__mutex_fastpath_lock_retval(atomic_t *count, int (*fail_fn)(atomic_t *))
+__mutex_fastpath_lock_retval(atomic_t *count)
 {
 	if (unlikely(__mutex_dec_return_lock(count) < 0))
-		return fail_fn(count);
+		return -1;
 	return 0;
 }
 

arch/powerpc/sysdev/fsl_pci.c

@@ -97,22 +97,14 @@ static int fsl_indirect_read_config(struct pci_bus *bus, unsigned int devfn,
 	return indirect_read_config(bus, devfn, offset, len, val);
 }
 
-static struct pci_ops fsl_indirect_pci_ops =
+#if defined(CONFIG_FSL_SOC_BOOKE) || defined(CONFIG_PPC_86xx)
+
+static struct pci_ops fsl_indirect_pcie_ops =
 {
 	.read = fsl_indirect_read_config,
 	.write = indirect_write_config,
 };
 
-static void __init fsl_setup_indirect_pci(struct pci_controller* hose,
-					  resource_size_t cfg_addr,
-					  resource_size_t cfg_data, u32 flags)
-{
-	setup_indirect_pci(hose, cfg_addr, cfg_data, flags);
-	hose->ops = &fsl_indirect_pci_ops;
-}
-
-#if defined(CONFIG_FSL_SOC_BOOKE) || defined(CONFIG_PPC_86xx)
-
 #define MAX_PHYS_ADDR_BITS	40
 static u64 pci64_dma_offset = 1ull << MAX_PHYS_ADDR_BITS;
 
@@ -504,13 +496,15 @@ int __init fsl_add_bridge(struct platform_device *pdev, int is_primary)
 	if (!hose->private_data)
 		goto no_bridge;
 
-	fsl_setup_indirect_pci(hose, rsrc.start, rsrc.start + 0x4,
+	setup_indirect_pci(hose, rsrc.start, rsrc.start + 0x4,
 			   PPC_INDIRECT_TYPE_BIG_ENDIAN);
 
 	if (in_be32(&pci->block_rev1) < PCIE_IP_REV_3_0)
 		hose->indirect_type |= PPC_INDIRECT_TYPE_FSL_CFG_REG_LINK;
 
 	if (early_find_capability(hose, 0, 0, PCI_CAP_ID_EXP)) {
+		/* use fsl_indirect_read_config for PCIe */
+		hose->ops = &fsl_indirect_pcie_ops;
 		/* For PCIE read HEADER_TYPE to identify controler mode */
 		early_read_config_byte(hose, 0, 0, PCI_HEADER_TYPE, &hdr_type);
 		if ((hdr_type & 0x7f) != PCI_HEADER_TYPE_BRIDGE)
@@ -814,7 +808,7 @@ int __init mpc83xx_add_bridge(struct device_node *dev)
 		if (ret)
 			goto err0;
 	} else {
-		fsl_setup_indirect_pci(hose, rsrc_cfg.start,
+		setup_indirect_pci(hose, rsrc_cfg.start,
 				   rsrc_cfg.start + 4, 0);
 	}
 

arch/s390/include/asm/dma-mapping.h

@@ -50,9 +50,10 @@ static inline int dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
 {
 	struct dma_map_ops *dma_ops = get_dma_ops(dev);
 
+	debug_dma_mapping_error(dev, dma_addr);
 	if (dma_ops->mapping_error)
 		return dma_ops->mapping_error(dev, dma_addr);
-	return (dma_addr == 0UL);
+	return (dma_addr == DMA_ERROR_CODE);
 }
 
 static inline void *dma_alloc_coherent(struct device *dev, size_t size,

arch/s390/kernel/ipl.c

@@ -754,9 +754,9 @@ static struct bin_attribute sys_reipl_fcp_scp_data_attr = {
 	.write = reipl_fcp_scpdata_write,
 };
 
-DEFINE_IPL_ATTR_RW(reipl_fcp, wwpn, "0x%016llx\n", "%016llx\n",
+DEFINE_IPL_ATTR_RW(reipl_fcp, wwpn, "0x%016llx\n", "%llx\n",
 		   reipl_block_fcp->ipl_info.fcp.wwpn);
-DEFINE_IPL_ATTR_RW(reipl_fcp, lun, "0x%016llx\n", "%016llx\n",
+DEFINE_IPL_ATTR_RW(reipl_fcp, lun, "0x%016llx\n", "%llx\n",
 		   reipl_block_fcp->ipl_info.fcp.lun);
 DEFINE_IPL_ATTR_RW(reipl_fcp, bootprog, "%lld\n", "%lld\n",
 		   reipl_block_fcp->ipl_info.fcp.bootprog);
@@ -1323,9 +1323,9 @@ static struct shutdown_action __refdata reipl_action = {
 
 /* FCP dump device attributes */
 
-DEFINE_IPL_ATTR_RW(dump_fcp, wwpn, "0x%016llx\n", "%016llx\n",
+DEFINE_IPL_ATTR_RW(dump_fcp, wwpn, "0x%016llx\n", "%llx\n",
 		   dump_block_fcp->ipl_info.fcp.wwpn);
-DEFINE_IPL_ATTR_RW(dump_fcp, lun, "0x%016llx\n", "%016llx\n",
+DEFINE_IPL_ATTR_RW(dump_fcp, lun, "0x%016llx\n", "%llx\n",
 		   dump_block_fcp->ipl_info.fcp.lun);
 DEFINE_IPL_ATTR_RW(dump_fcp, bootprog, "%lld\n", "%lld\n",
 		   dump_block_fcp->ipl_info.fcp.bootprog);

arch/s390/kernel/irq.c

@@ -312,6 +312,7 @@ void measurement_alert_subclass_unregister(void)
 }
 EXPORT_SYMBOL(measurement_alert_subclass_unregister);
 
+#ifdef CONFIG_SMP
 void synchronize_irq(unsigned int irq)
 {
 	/*
@@ -320,6 +321,7 @@ void synchronize_irq(unsigned int irq)
 	 */
 }
 EXPORT_SYMBOL_GPL(synchronize_irq);
+#endif
 
 #ifndef CONFIG_PCI
 

arch/s390/mm/mem_detect.c

@@ -123,7 +123,8 @@ void create_mem_hole(struct mem_chunk mem_chunk[], unsigned long addr,
 			continue;
 		} else if ((addr <= chunk->addr) &&
 			   (addr + size >= chunk->addr + chunk->size)) {
-			memset(chunk, 0 , sizeof(*chunk));
+			memmove(chunk, chunk + 1, (MEMORY_CHUNKS-i-1) * sizeof(*chunk));
+			memset(&mem_chunk[MEMORY_CHUNKS-1], 0, sizeof(*chunk));
 		} else if (addr + size < chunk->addr + chunk->size) {
 			chunk->size =  chunk->addr + chunk->size - addr - size;
 			chunk->addr = addr + size;

arch/sh/include/asm/mutex-llsc.h

@@ -37,7 +37,7 @@ __mutex_fastpath_lock(atomic_t *count, void (*fail_fn)(atomic_t *))
 }
 
 static inline int
-__mutex_fastpath_lock_retval(atomic_t *count, int (*fail_fn)(atomic_t *))
+__mutex_fastpath_lock_retval(atomic_t *count)
 {
 	int __done, __res;
 
@@ -51,7 +51,7 @@ __mutex_fastpath_lock_retval(atomic_t *count, int (*fail_fn)(atomic_t *))
 		: "t");
 
 	if (unlikely(!__done || __res != 0))
-		__res = fail_fn(count);
+		__res = -1;
 
 	return __res;
 }

arch/x86/include/asm/mutex_32.h

@@ -42,17 +42,14 @@ do {								\
  *  __mutex_fastpath_lock_retval - try to take the lock by moving the count
  *                                 from 1 to a 0 value
  *  @count: pointer of type atomic_t
- *  @fail_fn: function to call if the original value was not 1
  *
- * Change the count from 1 to a value lower than 1, and call <fail_fn> if it
- * wasn't 1 originally. This function returns 0 if the fastpath succeeds,
- * or anything the slow path function returns
+ * Change the count from 1 to a value lower than 1. This function returns 0
+ * if the fastpath succeeds, or -1 otherwise.
  */
-static inline int __mutex_fastpath_lock_retval(atomic_t *count,
-					       int (*fail_fn)(atomic_t *))
+static inline int __mutex_fastpath_lock_retval(atomic_t *count)
 {
 	if (unlikely(atomic_dec_return(count) < 0))
-		return fail_fn(count);
+		return -1;
 	else
 		return 0;
 }

arch/x86/include/asm/mutex_64.h

@@ -37,17 +37,14 @@ do {								\
  *  __mutex_fastpath_lock_retval - try to take the lock by moving the count
  *                                 from 1 to a 0 value
  *  @count: pointer of type atomic_t
- *  @fail_fn: function to call if the original value was not 1
  *
- * Change the count from 1 to a value lower than 1, and call <fail_fn> if
- * it wasn't 1 originally. This function returns 0 if the fastpath succeeds,
- * or anything the slow path function returns
+ * Change the count from 1 to a value lower than 1. This function returns 0
+ * if the fastpath succeeds, or -1 otherwise.
  */
-static inline int __mutex_fastpath_lock_retval(atomic_t *count,
-					       int (*fail_fn)(atomic_t *))
+static inline int __mutex_fastpath_lock_retval(atomic_t *count)
 {
 	if (unlikely(atomic_dec_return(count) < 0))
-		return fail_fn(count);
+		return -1;
 	else
 		return 0;
 }

drivers/input/joystick/xpad.c

@@ -137,7 +137,7 @@ static const struct xpad_device {
 	{ 0x0738, 0x4540, "Mad Catz Beat Pad", MAP_DPAD_TO_BUTTONS, XTYPE_XBOX },
 	{ 0x0738, 0x4556, "Mad Catz Lynx Wireless Controller", 0, XTYPE_XBOX },
 	{ 0x0738, 0x4716, "Mad Catz Wired Xbox 360 Controller", 0, XTYPE_XBOX360 },
-	{ 0x0738, 0x4728, "Mad Catz Street Fighter IV FightPad", XTYPE_XBOX360 },
+	{ 0x0738, 0x4728, "Mad Catz Street Fighter IV FightPad", MAP_TRIGGERS_TO_BUTTONS, XTYPE_XBOX360 },
 	{ 0x0738, 0x4738, "Mad Catz Wired Xbox 360 Controller (SFIV)", MAP_TRIGGERS_TO_BUTTONS, XTYPE_XBOX360 },
 	{ 0x0738, 0x6040, "Mad Catz Beat Pad Pro", MAP_DPAD_TO_BUTTONS, XTYPE_XBOX },
 	{ 0x0738, 0xbeef, "Mad Catz JOYTECH NEO SE Advanced GamePad", XTYPE_XBOX360 },

drivers/input/keyboard/Kconfig

@@ -431,6 +431,7 @@ config KEYBOARD_TEGRA
 
 config KEYBOARD_OPENCORES
 	tristate "OpenCores Keyboard Controller"
+	depends on HAS_IOMEM
 	help
 	  Say Y here if you want to use the OpenCores Keyboard Controller
 	  http://www.opencores.org/project,keyboardcontroller

drivers/input/serio/Kconfig

@@ -205,6 +205,7 @@ config SERIO_XILINX_XPS_PS2
 
 config SERIO_ALTERA_PS2
 	tristate "Altera UP PS/2 controller"
+	depends on HAS_IOMEM
 	help
 	  Say Y here if you have Altera University Program PS/2 ports.
 

drivers/input/tablet/wacom_wac.c

@@ -363,6 +363,7 @@ static int wacom_intuos_inout(struct wacom_wac *wacom)
 		case 0x140802: /* Intuos4/5 13HD/24HD Classic Pen */
 		case 0x160802: /* Cintiq 13HD Pro Pen */
 		case 0x180802: /* DTH2242 Pen */
+		case 0x100802: /* Intuos4/5 13HD/24HD General Pen */
 			wacom->tool[idx] = BTN_TOOL_PEN;
 			break;
 
@@ -401,6 +402,7 @@ static int wacom_intuos_inout(struct wacom_wac *wacom)
 		case 0x10080c: /* Intuos4/5 13HD/24HD Art Pen Eraser */
 		case 0x16080a: /* Cintiq 13HD Pro Pen Eraser */
 		case 0x18080a: /* DTH2242 Eraser */
+		case 0x10080a: /* Intuos4/5 13HD/24HD General Pen Eraser */
 			wacom->tool[idx] = BTN_TOOL_RUBBER;
 			break;
 

drivers/input/touchscreen/cyttsp_core.c

@@ -116,6 +116,15 @@ static int ttsp_send_command(struct cyttsp *ts, u8 cmd)
 	return ttsp_write_block_data(ts, CY_REG_BASE, sizeof(cmd), &cmd);
 }
 
+static int cyttsp_handshake(struct cyttsp *ts)
+{
+	if (ts->pdata->use_hndshk)
+		return ttsp_send_command(ts,
+				ts->xy_data.hst_mode ^ CY_HNDSHK_BIT);
+
+	return 0;
+}
+
 static int cyttsp_load_bl_regs(struct cyttsp *ts)
 {
 	memset(&ts->bl_data, 0, sizeof(ts->bl_data));
@@ -133,7 +142,7 @@ static int cyttsp_exit_bl_mode(struct cyttsp *ts)
 	memcpy(bl_cmd, bl_command, sizeof(bl_command));
 	if (ts->pdata->bl_keys)
 		memcpy(&bl_cmd[sizeof(bl_command) - CY_NUM_BL_KEYS],
-			ts->pdata->bl_keys, sizeof(bl_command));
+			ts->pdata->bl_keys, CY_NUM_BL_KEYS);
 
 	error = ttsp_write_block_data(ts, CY_REG_BASE,
 				      sizeof(bl_cmd), bl_cmd);
@@ -167,6 +176,10 @@ static int cyttsp_set_operational_mode(struct cyttsp *ts)
 	if (error)
 		return error;
 
+	error = cyttsp_handshake(ts);
+	if (error)
+		return error;
+
 	return ts->xy_data.act_dist == CY_ACT_DIST_DFLT ? -EIO : 0;
 }
 
@@ -188,6 +201,10 @@ static int cyttsp_set_sysinfo_mode(struct cyttsp *ts)
 	if (error)
 		return error;
 
+	error = cyttsp_handshake(ts);
+	if (error)
+		return error;
+
 	if (!ts->sysinfo_data.tts_verh && !ts->sysinfo_data.tts_verl)
 		return -EIO;
 
@@ -344,12 +361,9 @@ static irqreturn_t cyttsp_irq(int irq, void *handle)
 		goto out;
 
 	/* provide flow control handshake */
-	if (ts->pdata->use_hndshk) {
-		error = ttsp_send_command(ts,
-				ts->xy_data.hst_mode ^ CY_HNDSHK_BIT);
+	error = cyttsp_handshake(ts);
 	if (error)
 		goto out;
-	}
 
 	if (unlikely(ts->state == CY_IDLE_STATE))
 		goto out;

drivers/input/touchscreen/cyttsp_core.h

@@ -67,8 +67,8 @@ struct cyttsp_xydata {
 /* TTSP System Information interface definition */
 struct cyttsp_sysinfo_data {
 	u8 hst_mode;
-	u8 mfg_cmd;
 	u8 mfg_stat;
+	u8 mfg_cmd;
 	u8 cid[3];
 	u8 tt_undef1;
 	u8 uid[8];

drivers/spi/spi-pxa2xx-dma.c

@@ -59,7 +59,7 @@ static int pxa2xx_spi_map_dma_buffer(struct driver_data *drv_data,
 		int ret;
 
 		sg_free_table(sgt);
-		ret = sg_alloc_table(sgt, nents, GFP_KERNEL);
+		ret = sg_alloc_table(sgt, nents, GFP_ATOMIC);
 		if (ret)
 			return ret;
 	}

drivers/spi/spi-pxa2xx.c

@@ -1075,7 +1075,7 @@ pxa2xx_spi_acpi_get_pdata(struct platform_device *pdev)
 	    acpi_bus_get_device(ACPI_HANDLE(&pdev->dev), &adev))
 		return NULL;
 
-	pdata = devm_kzalloc(&pdev->dev, sizeof(*ssp), GFP_KERNEL);
+	pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
 	if (!pdata) {
 		dev_err(&pdev->dev,
 			"failed to allocate memory for platform data\n");

drivers/spi/spi-s3c64xx.c

@@ -444,7 +444,7 @@ static int s3c64xx_spi_prepare_transfer(struct spi_master *spi)
 	}
 
 	ret = pm_runtime_get_sync(&sdd->pdev->dev);
-	if (ret != 0) {
+	if (ret < 0) {
 		dev_err(dev, "Failed to enable device: %d\n", ret);
 		goto out_tx;
 	}

fs/fuse/file.c

@@ -2470,12 +2470,15 @@ static long fuse_file_fallocate(struct file *file, int mode, loff_t offset,
 		.mode = mode
 	};
 	int err;
+	bool lock_inode = !(mode & FALLOC_FL_KEEP_SIZE) ||
+			   (mode & FALLOC_FL_PUNCH_HOLE);
 
 	if (fc->no_fallocate)
 		return -EOPNOTSUPP;
 
-	if (mode & FALLOC_FL_PUNCH_HOLE) {
+	if (lock_inode) {
 		mutex_lock(&inode->i_mutex);
+		if (mode & FALLOC_FL_PUNCH_HOLE)
 			fuse_set_nowrite(inode);
 	}
 
@@ -2511,7 +2514,8 @@ static long fuse_file_fallocate(struct file *file, int mode, loff_t offset,
 	fuse_invalidate_attr(inode);
 
 out:
-	if (mode & FALLOC_FL_PUNCH_HOLE) {
+	if (lock_inode) {
+		if (mode & FALLOC_FL_PUNCH_HOLE)
 			fuse_release_nowrite(inode);
 		mutex_unlock(&inode->i_mutex);
 	}

fs/splice.c

@@ -1283,6 +1283,7 @@ static int direct_splice_actor(struct pipe_inode_info *pipe,
  * @in:		file to splice from
  * @ppos:	input file offset
  * @out:	file to splice to
+ * @opos:	output file offset
  * @len:	number of bytes to splice
  * @flags:	splice modifier flags
  *

include/asm-generic/mutex-dec.h

@@ -28,17 +28,15 @@ __mutex_fastpath_lock(atomic_t *count, void (*fail_fn)(atomic_t *))
  *  __mutex_fastpath_lock_retval - try to take the lock by moving the count
  *                                 from 1 to a 0 value
  *  @count: pointer of type atomic_t
- *  @fail_fn: function to call if the original value was not 1
  *
- * Change the count from 1 to a value lower than 1, and call <fail_fn> if
- * it wasn't 1 originally. This function returns 0 if the fastpath succeeds,
- * or anything the slow path function returns.
+ * Change the count from 1 to a value lower than 1. This function returns 0
+ * if the fastpath succeeds, or -1 otherwise.
  */
 static inline int
-__mutex_fastpath_lock_retval(atomic_t *count, int (*fail_fn)(atomic_t *))
+__mutex_fastpath_lock_retval(atomic_t *count)
 {
 	if (unlikely(atomic_dec_return(count) < 0))
-		return fail_fn(count);
+		return -1;
 	return 0;
 }
 

include/asm-generic/mutex-null.h

@@ -11,7 +11,7 @@
 #define _ASM_GENERIC_MUTEX_NULL_H
 
 #define __mutex_fastpath_lock(count, fail_fn)		fail_fn(count)
-#define __mutex_fastpath_lock_retval(count, fail_fn)	fail_fn(count)
+#define __mutex_fastpath_lock_retval(count)		(-1)
 #define __mutex_fastpath_unlock(count, fail_fn)		fail_fn(count)
 #define __mutex_fastpath_trylock(count, fail_fn)	fail_fn(count)
 #define __mutex_slowpath_needs_to_unlock()		1

include/asm-generic/mutex-xchg.h

@@ -39,18 +39,16 @@ __mutex_fastpath_lock(atomic_t *count, void (*fail_fn)(atomic_t *))
  *  __mutex_fastpath_lock_retval - try to take the lock by moving the count
  *                                 from 1 to a 0 value
  *  @count: pointer of type atomic_t
- *  @fail_fn: function to call if the original value was not 1
  *
- * Change the count from 1 to a value lower than 1, and call <fail_fn> if it
- * wasn't 1 originally. This function returns 0 if the fastpath succeeds,
- * or anything the slow path function returns
+ * Change the count from 1 to a value lower than 1. This function returns 0
+ * if the fastpath succeeds, or -1 otherwise.
  */
 static inline int
-__mutex_fastpath_lock_retval(atomic_t *count, int (*fail_fn)(atomic_t *))
+__mutex_fastpath_lock_retval(atomic_t *count)
 {
 	if (unlikely(atomic_xchg(count, 0) != 1))
 		if (likely(atomic_xchg(count, -1) != 1))
-			return fail_fn(count);
+			return -1;
 	return 0;
 }
 

include/linux/mutex-debug.h

@@ -3,6 +3,7 @@
 
 #include <linux/linkage.h>
 #include <linux/lockdep.h>
+#include <linux/debug_locks.h>
 
 /*
  * Mutexes - debugging helpers:

lib/Kconfig.debug

@@ -547,6 +547,19 @@ config DEBUG_MUTEXES
 	 This feature allows mutex semantics violations to be detected and
 	 reported.
 
+config DEBUG_WW_MUTEX_SLOWPATH
+	bool "Wait/wound mutex debugging: Slowpath testing"
+	depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
+	select DEBUG_LOCK_ALLOC
+	select DEBUG_SPINLOCK
+	select DEBUG_MUTEXES
+	help
+	 This feature enables slowpath testing for w/w mutex users by
+	 injecting additional -EDEADLK wound/backoff cases. Together with
+	 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
+	 will test all possible w/w mutex interface abuse with the
+	 exception of simply not acquiring all the required locks.
+
 config DEBUG_LOCK_ALLOC
 	bool "Lock debugging: detect incorrect freeing of live locks"
 	depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT

lib/debug_locks.c

@@ -30,6 +30,7 @@ EXPORT_SYMBOL_GPL(debug_locks);
  * a locking bug is detected.
  */
 int debug_locks_silent;
+EXPORT_SYMBOL_GPL(debug_locks_silent);
 
 /*
  * Generic 'turn off all lock debugging' function:
@@ -44,3 +45,4 @@ int debug_locks_off(void)
 	}
 	return 0;
 }
+EXPORT_SYMBOL_GPL(debug_locks_off);