![Sasha Levin](/assets/img/avatar_default.png)
If the dummy evgen failed init, the irq allocation functions which assume init succeeded may still be called - causing an OOPS due to wrong assumption. Here's the oops: [ 3.914332] BUG: unable to handle kernel NULL pointer dereference at 0000000000000148 [ 3.915310] IP: [<ffffffff810b3008>] __lock_acquire+0xac/0xe50 [ 3.915310] PGD 0 [ 3.915310] Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC [ 3.915310] CPU 1 [ 3.915310] Pid: 1, comm: swapper Not tainted 3.2.0-rc2-sasha-00279-gd7bfb12-dirty #20 [ 3.915310] RIP: 0010:[<ffffffff810b3008>] [<ffffffff810b3008>] __lock_acquire+0xac/0xe50 [ 3.915310] RSP: 0018:ffff880012499bc0 EFLAGS: 00010046 [ 3.915310] RAX: 0000000000000086 RBX: ffff880012490000 RCX: 0000000000000000 [ 3.915310] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000148 [ 3.915310] RBP: ffff880012499c90 R08: 0000000000000002 R09: 0000000000000000 [ 3.915310] R10: 0000000000000148 R11: 0000000000000000 R12: 0000000000000148 [ 3.915310] R13: 0000000000000002 R14: 0000000000000000 R15: 0000000000000000 [ 3.915310] FS: 0000000000000000(0000) GS:ffff880013c00000(0000) knlGS:0000000000000000 [ 3.915310] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b [ 3.915310] CR2: 0000000000000148 CR3: 0000000002605000 CR4: 00000000000406e0 [ 3.915310] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 3.915310] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 [ 3.915310] Process swapper (pid: 1, threadinfo ffff880012498000, task ffff880012490000) [ 3.915310] Stack: [ 3.915310] ffff880012490000 ffffffff81e6fd38 ffffffff00000000 0000000000000000 [ 3.915310] 0000000000000148 0000000012499c08 ffffffff00000000 000000000000002e [ 3.915310] 0000000000000001 ffff880012499ce0 ffffffff8161620e 0000000000000000 [ 3.915310] Call Trace: [ 3.915310] [<ffffffff81e6fd38>] ? retint_restore_args+0x13/0x13 [ 3.915310] [<ffffffff8161620e>] ? trace_hardirqs_on_thunk+0x3a/0x3f [ 3.915310] [<ffffffff81e6fd38>] ? retint_restore_args+0x13/0x13 [ 3.915310] [<ffffffff81af8883>] ? iio_dummy_evgen_get_irq+0x33/0x8a [ 3.915310] [<ffffffff810b4255>] lock_acquire+0x8a/0xa7 [ 3.915310] [<ffffffff81af8883>] ? iio_dummy_evgen_get_irq+0x33/0x8a [ 3.915310] [<ffffffff81e6db81>] __mutex_lock_common+0x63/0x491 [ 3.915310] [<ffffffff81af8883>] ? iio_dummy_evgen_get_irq+0x33/0x8a [ 3.915310] [<ffffffff810b474d>] ? debug_check_no_locks_freed+0x135/0x14a [ 3.915310] [<ffffffff810b2c3a>] ? lock_is_held+0x92/0x9d [ 3.915310] [<ffffffff81e6dfe5>] mutex_lock_nested+0x36/0x3b [ 3.915310] [<ffffffff81af8883>] iio_dummy_evgen_get_irq+0x33/0x8a [ 3.915310] [<ffffffff81af8594>] iio_simple_dummy_events_register+0x1b/0x69 [ 3.915310] [<ffffffff82ad4a91>] iio_dummy_init+0x105/0x18d [ 3.915310] [<ffffffff82ad498c>] ? iio_init+0x7d/0x7d [ 3.915310] [<ffffffff82a8dc02>] do_one_initcall+0x7a/0x135 [ 3.915310] [<ffffffff82a8dda7>] kernel_init+0xea/0x16f [ 3.915310] [<ffffffff81e727c4>] kernel_thread_helper+0x4/0x10 [ 3.915310] [<ffffffff81e6fd38>] ? retint_restore_args+0x13/0x13 [ 3.915310] [<ffffffff82a8dcbd>] ? do_one_initcall+0x135/0x135 [ 3.915310] [<ffffffff81e727c0>] ? gs_change+0x13/0x13 [ 3.915310] Code: 95 50 ff ff ff 74 24 e8 1f 3f 56 00 85 c0 0f 84 4e 0d 00 00 be cf 0b 00 00 83 3d 63 7c 58 02 00 0f 85 3c 0d 00 00 e9 c1 0c 00 00 [ 3.915310] 81 3a a0 17 ca 82 b8 01 00 00 00 44 0f 44 e8 83 fe 01 77 0c [ 3.915310] RIP [<ffffffff810b3008>] __lock_acquire+0xac/0xe50 [ 3.915310] RSP <ffff880012499bc0> [ 3.915310] CR2: 0000000000000148 Acked-by: Jonathan Cameron <jic23@cam.ac.uk> Signed-off-by: Sasha Levin <levinsasha928@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
222 lines
6.1 KiB
C
222 lines
6.1 KiB
C
/**
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* Copyright (c) 2011 Jonathan Cameron
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 as published by
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* the Free Software Foundation.
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*
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* Companion module to the iio simple dummy example driver.
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* The purpose of this is to generate 'fake' event interrupts thus
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* allowing that driver's code to be as close as possible to that of
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* a normal driver talking to hardware. The approach used here
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* is not intended to be general and just happens to work for this
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* particular use case.
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*/
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#include <linux/kernel.h>
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#include <linux/slab.h>
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#include <linux/interrupt.h>
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#include <linux/irq.h>
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#include <linux/mutex.h>
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#include <linux/module.h>
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#include <linux/sysfs.h>
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#include "iio_dummy_evgen.h"
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#include "iio.h"
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#include "sysfs.h"
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/* Fiddly bit of faking and irq without hardware */
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#define IIO_EVENTGEN_NO 10
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/**
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* struct iio_dummy_evgen - evgen state
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* @chip: irq chip we are faking
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* @base: base of irq range
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* @enabled: mask of which irqs are enabled
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* @inuse: mask of which irqs actually have anyone connected
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* @lock: protect the evgen state
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*/
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struct iio_dummy_eventgen {
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struct irq_chip chip;
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int base;
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bool enabled[IIO_EVENTGEN_NO];
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bool inuse[IIO_EVENTGEN_NO];
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struct mutex lock;
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};
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/* We can only ever have one instance of this 'device' */
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static struct iio_dummy_eventgen *iio_evgen;
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static const char *iio_evgen_name = "iio_dummy_evgen";
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static void iio_dummy_event_irqmask(struct irq_data *d)
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{
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struct irq_chip *chip = irq_data_get_irq_chip(d);
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struct iio_dummy_eventgen *evgen =
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container_of(chip, struct iio_dummy_eventgen, chip);
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evgen->enabled[d->irq - evgen->base] = false;
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}
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static void iio_dummy_event_irqunmask(struct irq_data *d)
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{
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struct irq_chip *chip = irq_data_get_irq_chip(d);
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struct iio_dummy_eventgen *evgen =
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container_of(chip, struct iio_dummy_eventgen, chip);
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evgen->enabled[d->irq - evgen->base] = true;
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}
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static int iio_dummy_evgen_create(void)
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{
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int ret, i;
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iio_evgen = kzalloc(sizeof(*iio_evgen), GFP_KERNEL);
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if (iio_evgen == NULL)
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return -ENOMEM;
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iio_evgen->base = irq_alloc_descs(-1, 0, IIO_EVENTGEN_NO, 0);
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if (iio_evgen->base < 0) {
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ret = iio_evgen->base;
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kfree(iio_evgen);
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return ret;
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}
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iio_evgen->chip.name = iio_evgen_name;
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iio_evgen->chip.irq_mask = &iio_dummy_event_irqmask;
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iio_evgen->chip.irq_unmask = &iio_dummy_event_irqunmask;
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for (i = 0; i < IIO_EVENTGEN_NO; i++) {
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irq_set_chip(iio_evgen->base + i, &iio_evgen->chip);
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irq_set_handler(iio_evgen->base + i, &handle_simple_irq);
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irq_modify_status(iio_evgen->base + i,
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IRQ_NOREQUEST | IRQ_NOAUTOEN,
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IRQ_NOPROBE);
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}
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mutex_init(&iio_evgen->lock);
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return 0;
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}
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/**
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* iio_dummy_evgen_get_irq() - get an evgen provided irq for a device
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*
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* This function will give a free allocated irq to a client device.
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* That irq can then be caused to 'fire' by using the associated sysfs file.
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*/
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int iio_dummy_evgen_get_irq(void)
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{
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int i, ret = 0;
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if (iio_evgen == NULL)
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return -ENODEV;
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mutex_lock(&iio_evgen->lock);
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for (i = 0; i < IIO_EVENTGEN_NO; i++)
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if (iio_evgen->inuse[i] == false) {
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ret = iio_evgen->base + i;
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iio_evgen->inuse[i] = true;
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break;
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}
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mutex_unlock(&iio_evgen->lock);
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if (i == IIO_EVENTGEN_NO)
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return -ENOMEM;
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return ret;
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}
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EXPORT_SYMBOL_GPL(iio_dummy_evgen_get_irq);
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/**
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* iio_dummy_evgen_release_irq() - give the irq back.
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* @irq: irq being returned to the pool
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*
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* Used by client driver instances to give the irqs back when they disconnect
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*/
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int iio_dummy_evgen_release_irq(int irq)
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{
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mutex_lock(&iio_evgen->lock);
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iio_evgen->inuse[irq - iio_evgen->base] = false;
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mutex_unlock(&iio_evgen->lock);
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return 0;
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}
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EXPORT_SYMBOL_GPL(iio_dummy_evgen_release_irq);
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static void iio_dummy_evgen_free(void)
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{
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irq_free_descs(iio_evgen->base, IIO_EVENTGEN_NO);
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kfree(iio_evgen);
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}
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static void iio_evgen_release(struct device *dev)
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{
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iio_dummy_evgen_free();
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}
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static ssize_t iio_evgen_poke(struct device *dev,
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struct device_attribute *attr,
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const char *buf,
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size_t len)
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{
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struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
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if (iio_evgen->enabled[this_attr->address])
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handle_nested_irq(iio_evgen->base + this_attr->address);
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return len;
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}
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static IIO_DEVICE_ATTR(poke_ev0, S_IWUSR, NULL, &iio_evgen_poke, 0);
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static IIO_DEVICE_ATTR(poke_ev1, S_IWUSR, NULL, &iio_evgen_poke, 1);
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static IIO_DEVICE_ATTR(poke_ev2, S_IWUSR, NULL, &iio_evgen_poke, 2);
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static IIO_DEVICE_ATTR(poke_ev3, S_IWUSR, NULL, &iio_evgen_poke, 3);
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static IIO_DEVICE_ATTR(poke_ev4, S_IWUSR, NULL, &iio_evgen_poke, 4);
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static IIO_DEVICE_ATTR(poke_ev5, S_IWUSR, NULL, &iio_evgen_poke, 5);
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static IIO_DEVICE_ATTR(poke_ev6, S_IWUSR, NULL, &iio_evgen_poke, 6);
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static IIO_DEVICE_ATTR(poke_ev7, S_IWUSR, NULL, &iio_evgen_poke, 7);
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static IIO_DEVICE_ATTR(poke_ev8, S_IWUSR, NULL, &iio_evgen_poke, 8);
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static IIO_DEVICE_ATTR(poke_ev9, S_IWUSR, NULL, &iio_evgen_poke, 9);
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static struct attribute *iio_evgen_attrs[] = {
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&iio_dev_attr_poke_ev0.dev_attr.attr,
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&iio_dev_attr_poke_ev1.dev_attr.attr,
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&iio_dev_attr_poke_ev2.dev_attr.attr,
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&iio_dev_attr_poke_ev3.dev_attr.attr,
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&iio_dev_attr_poke_ev4.dev_attr.attr,
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&iio_dev_attr_poke_ev5.dev_attr.attr,
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&iio_dev_attr_poke_ev6.dev_attr.attr,
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&iio_dev_attr_poke_ev7.dev_attr.attr,
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&iio_dev_attr_poke_ev8.dev_attr.attr,
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&iio_dev_attr_poke_ev9.dev_attr.attr,
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NULL,
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};
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static const struct attribute_group iio_evgen_group = {
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.attrs = iio_evgen_attrs,
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};
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static const struct attribute_group *iio_evgen_groups[] = {
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&iio_evgen_group,
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NULL
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};
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static struct device iio_evgen_dev = {
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.bus = &iio_bus_type,
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.groups = iio_evgen_groups,
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.release = &iio_evgen_release,
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};
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static __init int iio_dummy_evgen_init(void)
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{
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int ret = iio_dummy_evgen_create();
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if (ret < 0)
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return ret;
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device_initialize(&iio_evgen_dev);
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dev_set_name(&iio_evgen_dev, "iio_evgen");
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return device_add(&iio_evgen_dev);
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}
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module_init(iio_dummy_evgen_init);
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static __exit void iio_dummy_evgen_exit(void)
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{
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device_unregister(&iio_evgen_dev);
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}
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module_exit(iio_dummy_evgen_exit);
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MODULE_AUTHOR("Jonathan Cameron <jic23@cam.ac.uk>");
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MODULE_DESCRIPTION("IIO dummy driver");
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MODULE_LICENSE("GPL v2");
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