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
Cc: Jonathan Cameron <jic23@xxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxx>
Cc: linux-iio@xxxxxxxxxxxxxxx
Cc: devel@xxxxxxxxxxxxxxxxxxxx
Signed-off-by: Sasha Levin <levinsasha928@xxxxxxxxx>
---
drivers/staging/iio/iio_dummy_evgen.c | 7 +++++++
1 files changed, 7 insertions(+), 0 deletions(-)
diff --git a/drivers/staging/iio/iio_dummy_evgen.c b/drivers/staging/iio/iio_dummy_evgen.c
index da657d1..74d8d94 100644
--- a/drivers/staging/iio/iio_dummy_evgen.c
+++ b/drivers/staging/iio/iio_dummy_evgen.c
@@ -102,6 +102,10 @@ static int iio_dummy_evgen_create(void)
int iio_dummy_evgen_get_irq(void)
{
int i, ret = 0;
+
+ if (iio_evgen == NULL)
+ return -ENODEV;
+
mutex_lock(&iio_evgen->lock);
for (i = 0; i < IIO_EVENTGEN_NO; i++)
if (iio_evgen->inuse[i] == false) {
@@ -124,6 +128,9 @@ EXPORT_SYMBOL_GPL(iio_dummy_evgen_get_irq);
*/
int iio_dummy_evgen_release_irq(int irq)
{
+ if (iio_evgen == NULL)
+ return -ENODEV;
+
mutex_lock(&iio_evgen->lock);
iio_evgen->inuse[irq - iio_evgen->base] = false;
mutex_unlock(&iio_evgen->lock);
--
1.7.8.rc1
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