From 153bedbac2ebd475e1c7c2d2fa0c042f5525927d Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Fri, 8 Nov 2019 17:08:55 +0100 Subject: irq_work: Convert flags to atomic_t We need to convert flags to atomic_t in order to later fix an ordering issue on atomic_cmpxchg() failure. This will allow us to use atomic_fetch_or(). Also clarify the nature of those flags. [ mingo: Converted two more usage site the original patch missed. ] Signed-off-by: Frederic Weisbecker Cc: Linus Torvalds Cc: Paul E . McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Link: https://lkml.kernel.org/r/20191108160858.31665-2-frederic@kernel.org Signed-off-by: Ingo Molnar --- kernel/bpf/stackmap.c | 2 +- kernel/irq_work.c | 18 +++++++++--------- kernel/printk/printk.c | 2 +- kernel/trace/bpf_trace.c | 2 +- 4 files changed, 12 insertions(+), 12 deletions(-) (limited to 'kernel') diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c index 052580c33d26..4d31284095e2 100644 --- a/kernel/bpf/stackmap.c +++ b/kernel/bpf/stackmap.c @@ -289,7 +289,7 @@ static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs, if (in_nmi()) { work = this_cpu_ptr(&up_read_work); - if (work->irq_work.flags & IRQ_WORK_BUSY) + if (atomic_read(&work->irq_work.flags) & IRQ_WORK_BUSY) /* cannot queue more up_read, fallback */ irq_work_busy = true; } diff --git a/kernel/irq_work.c b/kernel/irq_work.c index d42acaf81886..df0dbf4d859b 100644 --- a/kernel/irq_work.c +++ b/kernel/irq_work.c @@ -29,16 +29,16 @@ static DEFINE_PER_CPU(struct llist_head, lazy_list); */ static bool irq_work_claim(struct irq_work *work) { - unsigned long flags, oflags, nflags; + int flags, oflags, nflags; /* * Start with our best wish as a premise but only trust any * flag value after cmpxchg() result. */ - flags = work->flags & ~IRQ_WORK_PENDING; + flags = atomic_read(&work->flags) & ~IRQ_WORK_PENDING; for (;;) { nflags = flags | IRQ_WORK_CLAIMED; - oflags = cmpxchg(&work->flags, flags, nflags); + oflags = atomic_cmpxchg(&work->flags, flags, nflags); if (oflags == flags) break; if (oflags & IRQ_WORK_PENDING) @@ -61,7 +61,7 @@ void __weak arch_irq_work_raise(void) static void __irq_work_queue_local(struct irq_work *work) { /* If the work is "lazy", handle it from next tick if any */ - if (work->flags & IRQ_WORK_LAZY) { + if (atomic_read(&work->flags) & IRQ_WORK_LAZY) { if (llist_add(&work->llnode, this_cpu_ptr(&lazy_list)) && tick_nohz_tick_stopped()) arch_irq_work_raise(); @@ -143,7 +143,7 @@ static void irq_work_run_list(struct llist_head *list) { struct irq_work *work, *tmp; struct llist_node *llnode; - unsigned long flags; + int flags; BUG_ON(!irqs_disabled()); @@ -159,15 +159,15 @@ static void irq_work_run_list(struct llist_head *list) * to claim that work don't rely on us to handle their data * while we are in the middle of the func. */ - flags = work->flags & ~IRQ_WORK_PENDING; - xchg(&work->flags, flags); + flags = atomic_read(&work->flags) & ~IRQ_WORK_PENDING; + atomic_xchg(&work->flags, flags); work->func(work); /* * Clear the BUSY bit and return to the free state if * no-one else claimed it meanwhile. */ - (void)cmpxchg(&work->flags, flags, flags & ~IRQ_WORK_BUSY); + (void)atomic_cmpxchg(&work->flags, flags, flags & ~IRQ_WORK_BUSY); } } @@ -199,7 +199,7 @@ void irq_work_sync(struct irq_work *work) { lockdep_assert_irqs_enabled(); - while (work->flags & IRQ_WORK_BUSY) + while (atomic_read(&work->flags) & IRQ_WORK_BUSY) cpu_relax(); } EXPORT_SYMBOL_GPL(irq_work_sync); diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index ca65327a6de8..865727373a3b 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -2961,7 +2961,7 @@ static void wake_up_klogd_work_func(struct irq_work *irq_work) static DEFINE_PER_CPU(struct irq_work, wake_up_klogd_work) = { .func = wake_up_klogd_work_func, - .flags = IRQ_WORK_LAZY, + .flags = ATOMIC_INIT(IRQ_WORK_LAZY), }; void wake_up_klogd(void) diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 44bd08f2443b..ff467a4e2639 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -660,7 +660,7 @@ BPF_CALL_1(bpf_send_signal, u32, sig) return -EINVAL; work = this_cpu_ptr(&send_signal_work); - if (work->irq_work.flags & IRQ_WORK_BUSY) + if (atomic_read(&work->irq_work.flags) & IRQ_WORK_BUSY) return -EBUSY; /* Add the current task, which is the target of sending signal, -- cgit v1.2.3 From 25269871db1ad0cbbaafd5098cbdb40c8db4ccb9 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Fri, 8 Nov 2019 17:08:56 +0100 Subject: irq_work: Fix irq_work_claim() memory ordering When irq_work_claim() finds IRQ_WORK_PENDING flag already set, we just return and don't raise a new IPI. We expect the destination to see and handle our latest updades thanks to the pairing atomic_xchg() in irq_work_run_list(). But cmpxchg() doesn't guarantee a full memory barrier upon failure. So it's possible that the destination misses our latest updates. So use atomic_fetch_or() instead that is unconditionally fully ordered and also performs exactly what we want here and simplify the code. Signed-off-by: Frederic Weisbecker Cc: Linus Torvalds Cc: Paul E . McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Link: https://lkml.kernel.org/r/20191108160858.31665-3-frederic@kernel.org Signed-off-by: Ingo Molnar --- kernel/irq_work.c | 22 +++++++--------------- 1 file changed, 7 insertions(+), 15 deletions(-) (limited to 'kernel') diff --git a/kernel/irq_work.c b/kernel/irq_work.c index df0dbf4d859b..255454a48346 100644 --- a/kernel/irq_work.c +++ b/kernel/irq_work.c @@ -29,24 +29,16 @@ static DEFINE_PER_CPU(struct llist_head, lazy_list); */ static bool irq_work_claim(struct irq_work *work) { - int flags, oflags, nflags; + int oflags; + oflags = atomic_fetch_or(IRQ_WORK_CLAIMED, &work->flags); /* - * Start with our best wish as a premise but only trust any - * flag value after cmpxchg() result. + * If the work is already pending, no need to raise the IPI. + * The pairing atomic_xchg() in irq_work_run() makes sure + * everything we did before is visible. */ - flags = atomic_read(&work->flags) & ~IRQ_WORK_PENDING; - for (;;) { - nflags = flags | IRQ_WORK_CLAIMED; - oflags = atomic_cmpxchg(&work->flags, flags, nflags); - if (oflags == flags) - break; - if (oflags & IRQ_WORK_PENDING) - return false; - flags = oflags; - cpu_relax(); - } - + if (oflags & IRQ_WORK_PENDING) + return false; return true; } -- cgit v1.2.3 From feb4a51323babe13315c3b783ea7f1cf25368918 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Fri, 8 Nov 2019 17:08:57 +0100 Subject: irq_work: Slightly simplify IRQ_WORK_PENDING clearing Instead of fetching the value of flags and perform an xchg() to clear a bit, just use atomic_fetch_andnot() that is more suitable to do that job in one operation while keeping the full ordering. Signed-off-by: Frederic Weisbecker Cc: Linus Torvalds Cc: Paul E . McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Link: https://lkml.kernel.org/r/20191108160858.31665-4-frederic@kernel.org Signed-off-by: Ingo Molnar --- kernel/irq_work.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) (limited to 'kernel') diff --git a/kernel/irq_work.c b/kernel/irq_work.c index 255454a48346..49c53f80a13a 100644 --- a/kernel/irq_work.c +++ b/kernel/irq_work.c @@ -34,7 +34,7 @@ static bool irq_work_claim(struct irq_work *work) oflags = atomic_fetch_or(IRQ_WORK_CLAIMED, &work->flags); /* * If the work is already pending, no need to raise the IPI. - * The pairing atomic_xchg() in irq_work_run() makes sure + * The pairing atomic_fetch_andnot() in irq_work_run() makes sure * everything we did before is visible. */ if (oflags & IRQ_WORK_PENDING) @@ -135,7 +135,6 @@ static void irq_work_run_list(struct llist_head *list) { struct irq_work *work, *tmp; struct llist_node *llnode; - int flags; BUG_ON(!irqs_disabled()); @@ -144,6 +143,7 @@ static void irq_work_run_list(struct llist_head *list) llnode = llist_del_all(list); llist_for_each_entry_safe(work, tmp, llnode, llnode) { + int flags; /* * Clear the PENDING bit, after this point the @work * can be re-used. @@ -151,8 +151,7 @@ static void irq_work_run_list(struct llist_head *list) * to claim that work don't rely on us to handle their data * while we are in the middle of the func. */ - flags = atomic_read(&work->flags) & ~IRQ_WORK_PENDING; - atomic_xchg(&work->flags, flags); + flags = atomic_fetch_andnot(IRQ_WORK_PENDING, &work->flags); work->func(work); /* -- cgit v1.2.3 From e9838bd51169af87ae248336d4c3fc59184a0e46 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Wed, 13 Nov 2019 18:12:01 +0100 Subject: irq_work: Fix IRQ_WORK_BUSY bit clearing While attempting to clear the busy bit at the end of a work execution, atomic_cmpxchg() expects the value of the flags with the pending bit cleared as the old value. However by mistake the value of the flags is passed without clearing the pending bit first. As a result, clearing the busy bit fails and irq_work_sync() may stall: watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [blktrace:4948] CPU: 0 PID: 4948 Comm: blktrace Not tainted 5.4.0-rc7-00003-gfeb4a51323bab #1 RIP: 0010:irq_work_sync+0x4/0x10 Call Trace: relay_close_buf+0x19/0x50 relay_close+0x64/0x100 blk_trace_free+0x1f/0x50 __blk_trace_remove+0x1e/0x30 blk_trace_ioctl+0x11b/0x140 blkdev_ioctl+0x6c1/0xa40 block_ioctl+0x39/0x40 do_vfs_ioctl+0xa5/0x700 ksys_ioctl+0x70/0x80 __x64_sys_ioctl+0x16/0x20 do_syscall_64+0x5b/0x1d0 entry_SYSCALL_64_after_hwframe+0x44/0xa9 So clear the appropriate bit before passing the old flags to cmpxchg(). Fixes: feb4a51323ba ("irq_work: Slightly simplify IRQ_WORK_PENDING clearing") Reported-by: kernel test robot Reported-by: Leonard Crestez Signed-off-by: Frederic Weisbecker Signed-off-by: Thomas Gleixner Tested-by: Leonard Crestez Link: https://lkml.kernel.org/r/20191113171201.14032-1-frederic@kernel.org --- kernel/irq_work.c | 1 + 1 file changed, 1 insertion(+) (limited to 'kernel') diff --git a/kernel/irq_work.c b/kernel/irq_work.c index 49c53f80a13a..828cc30774bc 100644 --- a/kernel/irq_work.c +++ b/kernel/irq_work.c @@ -158,6 +158,7 @@ static void irq_work_run_list(struct llist_head *list) * Clear the BUSY bit and return to the free state if * no-one else claimed it meanwhile. */ + flags &= ~IRQ_WORK_PENDING; (void)atomic_cmpxchg(&work->flags, flags, flags & ~IRQ_WORK_BUSY); } } -- cgit v1.2.3 From 20a15ee040f23bd553d4e6bbb1f8724ccd282abc Mon Sep 17 00:00:00 2001 From: luanshi Date: Wed, 13 Nov 2019 22:41:33 +0800 Subject: genirq: Fix function documentation of __irq_alloc_descs() The function got renamed at some point, but the kernel-doc was not updated. Signed-off-by: Liguang Zhang Signed-off-by: Thomas Gleixner Link: https://lkml.kernel.org/r/1573656093-8643-1-git-send-email-zhangliguang@linux.alibaba.com --- kernel/irq/irqdesc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c index 9be995fc3c5a..5b8fdd659e54 100644 --- a/kernel/irq/irqdesc.c +++ b/kernel/irq/irqdesc.c @@ -750,7 +750,7 @@ void irq_free_descs(unsigned int from, unsigned int cnt) EXPORT_SYMBOL_GPL(irq_free_descs); /** - * irq_alloc_descs - allocate and initialize a range of irq descriptors + * __irq_alloc_descs - allocate and initialize a range of irq descriptors * @irq: Allocate for specific irq number if irq >= 0 * @from: Start the search from this irq number * @cnt: Number of consecutive irqs to allocate. -- cgit v1.2.3 From 4a169a95d885fe5c050bac1a21d43c86ba955bcf Mon Sep 17 00:00:00 2001 From: Maulik Shah Date: Fri, 15 Nov 2019 15:11:49 -0700 Subject: genirq: Introduce irq_chip_get/set_parent_state calls On certain QTI chipsets some GPIOs are direct-connect interrupts to the GIC to be used as regular interrupt lines. When the GPIOs are not used for interrupt generation the interrupt line is disabled. But disabling the interrupt at GIC does not prevent the interrupt to be reported as pending at GIC_ISPEND. Later, when drivers call enable_irq() on the interrupt, an unwanted interrupt occurs. Introduce get and set methods for irqchip's parent to clear it's pending irq state. This then can be invoked by the GPIO interrupt controller on the parents in it hierarchy to clear the interrupt before enabling the interrupt. Signed-off-by: Maulik Shah Signed-off-by: Lina Iyer Signed-off-by: Marc Zyngier Reviewed-by: Stephen Boyd Link: https://lore.kernel.org/r/1573855915-9841-7-git-send-email-ilina@codeaurora.org [updated commit text and minor code fixes] --- kernel/irq/chip.c | 44 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+) (limited to 'kernel') diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c index b76703b2c0af..b3fa2d87d2f3 100644 --- a/kernel/irq/chip.c +++ b/kernel/irq/chip.c @@ -1297,6 +1297,50 @@ EXPORT_SYMBOL_GPL(handle_fasteoi_mask_irq); #endif /* CONFIG_IRQ_FASTEOI_HIERARCHY_HANDLERS */ +/** + * irq_chip_set_parent_state - set the state of a parent interrupt. + * + * @data: Pointer to interrupt specific data + * @which: State to be restored (one of IRQCHIP_STATE_*) + * @val: Value corresponding to @which + * + * Conditional success, if the underlying irqchip does not implement it. + */ +int irq_chip_set_parent_state(struct irq_data *data, + enum irqchip_irq_state which, + bool val) +{ + data = data->parent_data; + + if (!data || !data->chip->irq_set_irqchip_state) + return 0; + + return data->chip->irq_set_irqchip_state(data, which, val); +} +EXPORT_SYMBOL_GPL(irq_chip_set_parent_state); + +/** + * irq_chip_get_parent_state - get the state of a parent interrupt. + * + * @data: Pointer to interrupt specific data + * @which: one of IRQCHIP_STATE_* the caller wants to know + * @state: a pointer to a boolean where the state is to be stored + * + * Conditional success, if the underlying irqchip does not implement it. + */ +int irq_chip_get_parent_state(struct irq_data *data, + enum irqchip_irq_state which, + bool *state) +{ + data = data->parent_data; + + if (!data || !data->chip->irq_get_irqchip_state) + return 0; + + return data->chip->irq_get_irqchip_state(data, which, state); +} +EXPORT_SYMBOL_GPL(irq_chip_get_parent_state); + /** * irq_chip_enable_parent - Enable the parent interrupt (defaults to unmask if * NULL) -- cgit v1.2.3