From 665ca9187c4087736fa57b0e00bcf33ea601fb6f Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Sun, 31 Jan 2016 14:23:30 +0100 Subject: s390/stacktrace: fix save_stack_trace_tsk() for current task The function save_stack_trace_tsk() did not consider that it can be used for tsk == current, for which the current stack pointer obviously cannot be found in the thread structure. Fix this and get the stack pointer with an inline assembly. This fixes e.g. the output of "cat /proc/self/stack". Before: [<0000000000000000>] (null) [] 0xffffffffffffffff After: [<000000000011b3ee>] save_stack_trace_tsk+0x56/0x98 [<0000000000366cde>] proc_pid_stack+0xae/0x108 [<00000000003636f0>] proc_single_show+0x70/0xc0 [<0000000000311fbc>] seq_read+0xcc/0x448 [<00000000002e7716>] __vfs_read+0x36/0x100 [<00000000002e872e>] vfs_read+0x76/0x130 [<00000000002e975e>] SyS_read+0x66/0xd8 [<000000000089490e>] system_call+0xd6/0x264 [] 0xffffffffffffffff Signed-off-by: Heiko Carstens Tested-by: Peter Oberparleiter Signed-off-by: Martin Schwidefsky --- arch/s390/kernel/stacktrace.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/s390/kernel/stacktrace.c b/arch/s390/kernel/stacktrace.c index 5acba3cb7220..dd484c75be56 100644 --- a/arch/s390/kernel/stacktrace.c +++ b/arch/s390/kernel/stacktrace.c @@ -86,6 +86,10 @@ void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace) unsigned long sp, low, high; sp = tsk->thread.ksp; + if (tsk == current) { + /* Get current stack pointer. */ + asm volatile("la %0,0(15)" : "=a" (sp)); + } low = (unsigned long) task_stack_page(tsk); high = (unsigned long) task_pt_regs(tsk); save_context_stack(trace, sp, low, high, 0); -- cgit v1.2.3 From 9900c48c46d8bcf497972024c5fe366e6d9771f3 Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Mon, 1 Feb 2016 10:13:05 +0100 Subject: s390/stacktrace: fix address ranges for asynchronous and panic stack git commit dc7ee00d4771 ("s390: lowcore stack pointer offsets") introduced a regression in regard to save_stack_trace(). The stack pointer for the asynchronous and the panic stack in the lowcore now have an additional offset applied to them. This offset needs to be taken into account in the calculation for the low and high address for the stacks. This bug was already partially fixed with 9cc5c206d9b4 ("s390/dumpstack: fix address ranges for asynchronous and panic stack"). This patch fixes it also for the stacktrace code. Fixes: dc7ee00d4771 ("s390: lowcore stack pointer offsets") Signed-off-by: Heiko Carstens Tested-by: Peter Oberparleiter Signed-off-by: Martin Schwidefsky --- arch/s390/kernel/stacktrace.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/arch/s390/kernel/stacktrace.c b/arch/s390/kernel/stacktrace.c index dd484c75be56..225bed00aa92 100644 --- a/arch/s390/kernel/stacktrace.c +++ b/arch/s390/kernel/stacktrace.c @@ -62,17 +62,18 @@ static unsigned long save_context_stack(struct stack_trace *trace, void save_stack_trace(struct stack_trace *trace) { register unsigned long sp asm ("15"); - unsigned long orig_sp, new_sp; + unsigned long orig_sp, new_sp, frame_size; + frame_size = STACK_FRAME_OVERHEAD + sizeof(struct pt_regs); orig_sp = sp; new_sp = save_context_stack(trace, orig_sp, - S390_lowcore.panic_stack - PAGE_SIZE, - S390_lowcore.panic_stack, 1); + S390_lowcore.panic_stack + frame_size - PAGE_SIZE, + S390_lowcore.panic_stack + frame_size, 1); if (new_sp != orig_sp) return; new_sp = save_context_stack(trace, new_sp, - S390_lowcore.async_stack - ASYNC_SIZE, - S390_lowcore.async_stack, 1); + S390_lowcore.async_stack + frame_size - ASYNC_SIZE, + S390_lowcore.async_stack + frame_size, 1); if (new_sp != orig_sp) return; save_context_stack(trace, new_sp, -- cgit v1.2.3 From f6331aaccbd980a49bff1559d66abcbd46af5b0a Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Mon, 1 Feb 2016 14:06:57 +0100 Subject: s390/stacktrace: add missing end marker save_stack_trace() did not write the ULONG_MAX end marker if there is enough space left. So simply follow x86 and arm64. Signed-off-by: Heiko Carstens Tested-by: Peter Oberparleiter Signed-off-by: Martin Schwidefsky --- arch/s390/kernel/stacktrace.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/s390/kernel/stacktrace.c b/arch/s390/kernel/stacktrace.c index 225bed00aa92..75e6ea930692 100644 --- a/arch/s390/kernel/stacktrace.c +++ b/arch/s390/kernel/stacktrace.c @@ -79,6 +79,8 @@ void save_stack_trace(struct stack_trace *trace) save_context_stack(trace, new_sp, S390_lowcore.thread_info, S390_lowcore.thread_info + THREAD_SIZE, 1); + if (trace->nr_entries < trace->max_entries) + trace->entries[trace->nr_entries++] = ULONG_MAX; } EXPORT_SYMBOL_GPL(save_stack_trace); -- cgit v1.2.3 From 66adce8f1f9f3bcd743a0e72c10aa850df8c5fa7 Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Mon, 1 Feb 2016 14:14:04 +0100 Subject: s390/stacktrace: save full stack traces save_stack_trace() only saves the stack trace of the current context (interrupt or process context). This is different to what other architectures like x86 do, which save the full stack trace across different contexts. Also extract a __save_stack_trace() helper function which will be used by a follow on patch. Signed-off-by: Heiko Carstens Tested-by: Peter Oberparleiter Signed-off-by: Martin Schwidefsky --- arch/s390/kernel/stacktrace.c | 21 ++++++++++++--------- 1 file changed, 12 insertions(+), 9 deletions(-) diff --git a/arch/s390/kernel/stacktrace.c b/arch/s390/kernel/stacktrace.c index 75e6ea930692..e0fec2d8ac40 100644 --- a/arch/s390/kernel/stacktrace.c +++ b/arch/s390/kernel/stacktrace.c @@ -59,26 +59,29 @@ static unsigned long save_context_stack(struct stack_trace *trace, } } -void save_stack_trace(struct stack_trace *trace) +static void __save_stack_trace(struct stack_trace *trace, unsigned long sp) { - register unsigned long sp asm ("15"); - unsigned long orig_sp, new_sp, frame_size; + unsigned long new_sp, frame_size; frame_size = STACK_FRAME_OVERHEAD + sizeof(struct pt_regs); - orig_sp = sp; - new_sp = save_context_stack(trace, orig_sp, + new_sp = save_context_stack(trace, sp, S390_lowcore.panic_stack + frame_size - PAGE_SIZE, S390_lowcore.panic_stack + frame_size, 1); - if (new_sp != orig_sp) - return; new_sp = save_context_stack(trace, new_sp, S390_lowcore.async_stack + frame_size - ASYNC_SIZE, S390_lowcore.async_stack + frame_size, 1); - if (new_sp != orig_sp) - return; save_context_stack(trace, new_sp, S390_lowcore.thread_info, S390_lowcore.thread_info + THREAD_SIZE, 1); +} + +void save_stack_trace(struct stack_trace *trace) +{ + register unsigned long r15 asm ("15"); + unsigned long sp; + + sp = r15; + __save_stack_trace(trace, sp); if (trace->nr_entries < trace->max_entries) trace->entries[trace->nr_entries++] = ULONG_MAX; } -- cgit v1.2.3 From e0115875c04548255212ebd7dbd90bdbe1257f48 Mon Sep 17 00:00:00 2001 From: Pratyush Anand Date: Fri, 29 Jan 2016 10:50:28 +0530 Subject: s390/stacktrace: add save_stack_trace_regs() Implement save_stack_trace_regs, so that a stack trace of a kprobe event can be obtained. Without this we see following warning: "save_stack_trace_regs() not implemented yet." when we execute: echo stacktrace > /sys/kernel/debug/tracing/trace_options echo "p kfree" >> /sys/kernel/debug/tracing/kprobe_events echo 1 > /sys/kernel/debug/tracing/events/kprobes/enable Reported-by: Chunyu Hu Signed-off-by: Pratyush Anand [heiko.carstens@de.ibm.com]: changed patch to use __save_stack_trace() Signed-off-by: Heiko Carstens Tested-by: Peter Oberparleiter Signed-off-by: Martin Schwidefsky --- arch/s390/kernel/stacktrace.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/arch/s390/kernel/stacktrace.c b/arch/s390/kernel/stacktrace.c index e0fec2d8ac40..8f64ebd63767 100644 --- a/arch/s390/kernel/stacktrace.c +++ b/arch/s390/kernel/stacktrace.c @@ -103,3 +103,14 @@ void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace) trace->entries[trace->nr_entries++] = ULONG_MAX; } EXPORT_SYMBOL_GPL(save_stack_trace_tsk); + +void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace) +{ + unsigned long sp; + + sp = kernel_stack_pointer(regs); + __save_stack_trace(trace, sp); + if (trace->nr_entries < trace->max_entries) + trace->entries[trace->nr_entries++] = ULONG_MAX; +} +EXPORT_SYMBOL_GPL(save_stack_trace_regs); -- cgit v1.2.3 From 1f8cbb9c8365061d8b866e9b4f4403e029d57989 Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Tue, 9 Feb 2016 12:00:16 +0100 Subject: s390/perf_event: fix address range for asynchronous stack git commit dc7ee00d4771 ("s390: lowcore stack pointer offsets") introduced a regression in regard to perf_callchain_kernel(). The stack pointer for the asynchronous stack in the lowcore now has an additional offset applied. This offset needs to be taken into account in the calculation for the low and high address for the stack. This bug was already partially fixed with 9cc5c206d9b4 ("s390/dumpstack: fix address ranges for asynchronous and panic stack"). This patch fixes it also for the perf_event code. Fixes: dc7ee00d4771 ("s390: lowcore stack pointer offsets") Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky --- arch/s390/kernel/perf_event.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/arch/s390/kernel/perf_event.c b/arch/s390/kernel/perf_event.c index cfcba2dd9bb5..0943b11a2f6e 100644 --- a/arch/s390/kernel/perf_event.c +++ b/arch/s390/kernel/perf_event.c @@ -260,12 +260,13 @@ static unsigned long __store_trace(struct perf_callchain_entry *entry, void perf_callchain_kernel(struct perf_callchain_entry *entry, struct pt_regs *regs) { - unsigned long head; + unsigned long head, frame_size; struct stack_frame *head_sf; if (user_mode(regs)) return; + frame_size = STACK_FRAME_OVERHEAD + sizeof(struct pt_regs); head = regs->gprs[15]; head_sf = (struct stack_frame *) head; @@ -273,8 +274,9 @@ void perf_callchain_kernel(struct perf_callchain_entry *entry, return; head = head_sf->back_chain; - head = __store_trace(entry, head, S390_lowcore.async_stack - ASYNC_SIZE, - S390_lowcore.async_stack); + head = __store_trace(entry, head, + S390_lowcore.async_stack + frame_size - ASYNC_SIZE, + S390_lowcore.async_stack + frame_size); __store_trace(entry, head, S390_lowcore.thread_info, S390_lowcore.thread_info + THREAD_SIZE); -- cgit v1.2.3 From 232f5dd78586a684a7364a486b934e19384189dc Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Tue, 9 Feb 2016 12:03:31 +0100 Subject: s390/oprofile: fix address range for asynchronous stack git commit dc7ee00d4771 ("s390: lowcore stack pointer offsets") introduced a regression in regard to s390_backtrace(). The stack pointer for the asynchronous stack in the lowcore now has an additional offset applied. This offset needs to be taken into account in the calculation for the low and high address for the stack. This bug was already partially fixed with commit 9cc5c206d9b4 ("s390/dumpstack: fix address ranges for asynchronous and panic stack"). This patch fixes it also for the oprofile code. Fixes: dc7ee00d4771 ("s390: lowcore stack pointer offsets") Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky --- arch/s390/oprofile/backtrace.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/arch/s390/oprofile/backtrace.c b/arch/s390/oprofile/backtrace.c index fe0bfe370c45..1884e1759529 100644 --- a/arch/s390/oprofile/backtrace.c +++ b/arch/s390/oprofile/backtrace.c @@ -54,12 +54,13 @@ __show_trace(unsigned int *depth, unsigned long sp, void s390_backtrace(struct pt_regs * const regs, unsigned int depth) { - unsigned long head; + unsigned long head, frame_size; struct stack_frame* head_sf; if (user_mode(regs)) return; + frame_size = STACK_FRAME_OVERHEAD + sizeof(struct pt_regs); head = regs->gprs[15]; head_sf = (struct stack_frame*)head; @@ -68,8 +69,9 @@ void s390_backtrace(struct pt_regs * const regs, unsigned int depth) head = head_sf->back_chain; - head = __show_trace(&depth, head, S390_lowcore.async_stack - ASYNC_SIZE, - S390_lowcore.async_stack); + head = __show_trace(&depth, head, + S390_lowcore.async_stack + frame_size - ASYNC_SIZE, + S390_lowcore.async_stack + frame_size); __show_trace(&depth, head, S390_lowcore.thread_info, S390_lowcore.thread_info + THREAD_SIZE); -- cgit v1.2.3 From 0986d97741150b307775d56f587a73ea873a4f4d Mon Sep 17 00:00:00 2001 From: Christian Borntraeger Date: Tue, 9 Feb 2016 16:23:39 +0100 Subject: s390: fix DAT off memory access, e.g. on kdump commit 204ee2c56431 ("s390/irqflags: optimize irq restore") optimized irqrestore to really only care about interrupts and adapted the remaining low level users. One spot (memcpy_real) was not touched, though - fix it. Otherwise a kdump kernel will fail while reading the old kernel. As we re-enable irqs with a non-standard function we have to tell lockdep about that. Fixes: 204ee2c56431 ("s390/irqflags: optimize irq restore") Signed-off-by: Christian Borntraeger Signed-off-by: Martin Schwidefsky --- arch/s390/mm/maccess.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/s390/mm/maccess.c b/arch/s390/mm/maccess.c index fec59c067d0d..350b0acd7f52 100644 --- a/arch/s390/mm/maccess.c +++ b/arch/s390/mm/maccess.c @@ -101,7 +101,9 @@ int memcpy_real(void *dest, void *src, size_t count) local_irq_save(flags); __arch_local_irq_stnsm(0xfbUL); rc = __memcpy_real(dest, src, count); - local_irq_restore(flags); + if (!arch_irqs_disabled_flags(flags)) + trace_hardirqs_on(); + __arch_local_irq_ssm(flags); return rc; } -- cgit v1.2.3 From 020bf042e5b397479c1174081b935d0ff15d1a64 Mon Sep 17 00:00:00 2001 From: Stefan Haberland Date: Tue, 15 Dec 2015 10:16:43 +0100 Subject: s390/dasd: prevent incorrect length error under z/VM after PAV changes The channel checks the specified length and the provided amount of data for CCWs and provides an incorrect length error if the size does not match. Under z/VM with simulation activated the length may get changed. Having the suppress length indication bit set is stated as good CCW coding practice and avoids errors under z/VM. Cc: stable@vger.kernel.org Signed-off-by: Stefan Haberland Signed-off-by: Martin Schwidefsky --- drivers/s390/block/dasd_alias.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/s390/block/dasd_alias.c b/drivers/s390/block/dasd_alias.c index 184b1dbeb554..4ff914c0f13c 100644 --- a/drivers/s390/block/dasd_alias.c +++ b/drivers/s390/block/dasd_alias.c @@ -723,7 +723,7 @@ static int reset_summary_unit_check(struct alias_lcu *lcu, ASCEBC((char *) &cqr->magic, 4); ccw = cqr->cpaddr; ccw->cmd_code = DASD_ECKD_CCW_RSCK; - ccw->flags = 0 ; + ccw->flags = CCW_FLAG_SLI; ccw->count = 16; ccw->cda = (__u32)(addr_t) cqr->data; ((char *)cqr->data)[0] = reason; -- cgit v1.2.3 From 9d862ababb609439c5d6987f6d3ddd09e703aa0b Mon Sep 17 00:00:00 2001 From: Stefan Haberland Date: Tue, 15 Dec 2015 10:45:05 +0100 Subject: s390/dasd: fix refcount for PAV reassignment Add refcount to the DASD device when a summary unit check worker is scheduled. This prevents that the device is set offline with worker in place. Cc: stable@vger.kernel.org Signed-off-by: Stefan Haberland Signed-off-by: Martin Schwidefsky --- drivers/s390/block/dasd_alias.c | 21 ++++++++++++++++----- 1 file changed, 16 insertions(+), 5 deletions(-) diff --git a/drivers/s390/block/dasd_alias.c b/drivers/s390/block/dasd_alias.c index 4ff914c0f13c..286782c60da4 100644 --- a/drivers/s390/block/dasd_alias.c +++ b/drivers/s390/block/dasd_alias.c @@ -264,8 +264,10 @@ void dasd_alias_disconnect_device_from_lcu(struct dasd_device *device) spin_unlock_irqrestore(&lcu->lock, flags); cancel_work_sync(&lcu->suc_data.worker); spin_lock_irqsave(&lcu->lock, flags); - if (device == lcu->suc_data.device) + if (device == lcu->suc_data.device) { + dasd_put_device(device); lcu->suc_data.device = NULL; + } } was_pending = 0; if (device == lcu->ruac_data.device) { @@ -273,8 +275,10 @@ void dasd_alias_disconnect_device_from_lcu(struct dasd_device *device) was_pending = 1; cancel_delayed_work_sync(&lcu->ruac_data.dwork); spin_lock_irqsave(&lcu->lock, flags); - if (device == lcu->ruac_data.device) + if (device == lcu->ruac_data.device) { + dasd_put_device(device); lcu->ruac_data.device = NULL; + } } private->lcu = NULL; spin_unlock_irqrestore(&lcu->lock, flags); @@ -549,8 +553,10 @@ static void lcu_update_work(struct work_struct *work) if ((rc && (rc != -EOPNOTSUPP)) || (lcu->flags & NEED_UAC_UPDATE)) { DBF_DEV_EVENT(DBF_WARNING, device, "could not update" " alias data in lcu (rc = %d), retry later", rc); - schedule_delayed_work(&lcu->ruac_data.dwork, 30*HZ); + if (!schedule_delayed_work(&lcu->ruac_data.dwork, 30*HZ)) + dasd_put_device(device); } else { + dasd_put_device(device); lcu->ruac_data.device = NULL; lcu->flags &= ~UPDATE_PENDING; } @@ -593,8 +599,10 @@ static int _schedule_lcu_update(struct alias_lcu *lcu, */ if (!usedev) return -EINVAL; + dasd_get_device(usedev); lcu->ruac_data.device = usedev; - schedule_delayed_work(&lcu->ruac_data.dwork, 0); + if (!schedule_delayed_work(&lcu->ruac_data.dwork, 0)) + dasd_put_device(usedev); return 0; } @@ -930,6 +938,7 @@ static void summary_unit_check_handling_work(struct work_struct *work) /* 3. read new alias configuration */ _schedule_lcu_update(lcu, device); lcu->suc_data.device = NULL; + dasd_put_device(device); spin_unlock_irqrestore(&lcu->lock, flags); } @@ -989,6 +998,8 @@ void dasd_alias_handle_summary_unit_check(struct dasd_device *device, } lcu->suc_data.reason = reason; lcu->suc_data.device = device; + dasd_get_device(device); spin_unlock(&lcu->lock); - schedule_work(&lcu->suc_data.worker); + if (!schedule_work(&lcu->suc_data.worker)) + dasd_put_device(device); }; -- cgit v1.2.3 From f6c9b160233f9b5afe926b91b55589b706076640 Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Wed, 10 Feb 2016 14:13:24 +0100 Subject: s390/diag: avoid lockdep recursion The diagnose tracer will indirectly call back into the lockdep code when lockdep does not expect it (arch_spinlock). This causes lockdep to disable itself and therefore we don't have a working lock dependency validator anymore. This patch effectively disables tracing of diag 0x9c and 0x44 if lockdep is enabled. If however lockdep is enabled spinlocks are mainly implemented using a trylock variant, which will not issue any diag 0x9c or 0x44. So this change has hardly any effect on tracing except when arch_spinlock and friends are explicitly used. Reported-and-Tested-by: David Hildenbrand Signed-off-by: Heiko Carstens Reviewed-by: David Hildenbrand Acked-by: Martin Schwidefsky Signed-off-by: Martin Schwidefsky --- arch/s390/kernel/trace.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/s390/kernel/trace.c b/arch/s390/kernel/trace.c index 21a5df99552b..dde7654f5c68 100644 --- a/arch/s390/kernel/trace.c +++ b/arch/s390/kernel/trace.c @@ -18,6 +18,9 @@ void trace_s390_diagnose_norecursion(int diag_nr) unsigned long flags; unsigned int *depth; + /* Avoid lockdep recursion. */ + if (IS_ENABLED(CONFIG_LOCKDEP)) + return; local_irq_save(flags); depth = this_cpu_ptr(&diagnose_trace_depth); if (*depth == 0) { -- cgit v1.2.3 From 52499d93d6dec3872de3b982219af6d4c182a452 Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Fri, 12 Feb 2016 12:40:31 +0100 Subject: s390/maccess: reduce stnsm instructions When fixing the DAT off bug ("s390: fix DAT off memory access, e.g. on kdump") both Christian and I missed that we can save an additional stnsm instruction. This saves us a couple of cycles which could improve the speed of memcpy_real. Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky --- arch/s390/mm/maccess.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/arch/s390/mm/maccess.c b/arch/s390/mm/maccess.c index 350b0acd7f52..792f9c63fbca 100644 --- a/arch/s390/mm/maccess.c +++ b/arch/s390/mm/maccess.c @@ -93,15 +93,17 @@ static int __memcpy_real(void *dest, void *src, size_t count) */ int memcpy_real(void *dest, void *src, size_t count) { + int irqs_disabled, rc; unsigned long flags; - int rc; if (!count) return 0; - local_irq_save(flags); - __arch_local_irq_stnsm(0xfbUL); + flags = __arch_local_irq_stnsm(0xf8UL); + irqs_disabled = arch_irqs_disabled_flags(flags); + if (!irqs_disabled) + trace_hardirqs_off(); rc = __memcpy_real(dest, src, count); - if (!arch_irqs_disabled_flags(flags)) + if (!irqs_disabled) trace_hardirqs_on(); __arch_local_irq_ssm(flags); return rc; -- cgit v1.2.3 From 12d319b920fa673a4d5e7c1785c5dc82dcd15257 Mon Sep 17 00:00:00 2001 From: Stefan Haberland Date: Fri, 12 Feb 2016 14:50:52 +0100 Subject: s390/dasd: fix performance drop Commit ca369d51b ("sd: Fix device-imposed transfer length limits") introduced a new queue limit max_dev_sectors which limits the maximum sectors for requests. The default value leads to small dasd requests and therefor to a performance drop. Set the max_dev_sectors value to the same value as the max_hw_sectors to use the maximum available request size for DASD devices. Signed-off-by: Stefan Haberland Cc: stable@vger.kernel.org # 4.4+ Signed-off-by: Martin Schwidefsky --- drivers/s390/block/dasd.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/s390/block/dasd.c b/drivers/s390/block/dasd.c index 41605dac8309..c78db05e75b1 100644 --- a/drivers/s390/block/dasd.c +++ b/drivers/s390/block/dasd.c @@ -3035,6 +3035,7 @@ static void dasd_setup_queue(struct dasd_block *block) max = block->base->discipline->max_blocks << block->s2b_shift; } queue_flag_set_unlocked(QUEUE_FLAG_NONROT, block->request_queue); + block->request_queue->limits.max_dev_sectors = max; blk_queue_logical_block_size(block->request_queue, block->bp_block); blk_queue_max_hw_sectors(block->request_queue, max); -- cgit v1.2.3