On Sun, Jan 31, 2016 at 12:13 PM, Takashi Iwai <tiwai@xxxxxxx> wrote: > On Wed, 27 Jan 2016 13:31:05 +0100, > Dmitry Vyukov wrote: >> >> On Tue, Jan 26, 2016 at 3:51 PM, Takashi Iwai <tiwai@xxxxxxx> wrote: >> > On Sun, 24 Jan 2016 17:29:12 +0100, >> > Dmitry Vyukov wrote: >> >> >> >> Hello, >> >> >> >> The following program triggers WARNING in snd_rawmidi_transmit_ack: >> >> >> >> ------------[ cut here ]------------ >> >> WARNING: CPU: 1 PID: 20739 at sound/core/rawmidi.c:1136 >> >> snd_rawmidi_transmit_ack+0x275/0x400() >> >> Modules linked in: >> >> CPU: 1 PID: 20739 Comm: syz-executor Tainted: G W 4.4.0+ #276 >> >> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 >> >> 00000000ffffffff ffff8800346af8d8 ffffffff82999e2d 0000000000000000 >> >> ffff88002fea97c0 ffffffff86d3f920 ffff8800346af918 ffffffff81352089 >> >> ffffffff84f80bd5 ffffffff86d3f920 0000000000000470 ffff8800600b9b68 >> >> Call Trace: >> >> [< inline >] __dump_stack lib/dump_stack.c:15 >> >> [<ffffffff82999e2d>] dump_stack+0x6f/0xa2 lib/dump_stack.c:50 >> >> [<ffffffff81352089>] warn_slowpath_common+0xd9/0x140 kernel/panic.c:482 >> >> [<ffffffff813522b9>] warn_slowpath_null+0x29/0x30 kernel/panic.c:515 >> >> [<ffffffff84f80bd5>] snd_rawmidi_transmit_ack+0x275/0x400 >> >> sound/core/rawmidi.c:1136 >> >> [<ffffffff84fdb3c1>] snd_virmidi_output_trigger+0x4b1/0x5a0 >> >> sound/core/seq/seq_virmidi.c:163 >> >> [< inline >] snd_rawmidi_output_trigger sound/core/rawmidi.c:150 >> >> [<ffffffff84f87ed9>] snd_rawmidi_kernel_write1+0x549/0x780 >> >> sound/core/rawmidi.c:1223 >> >> [<ffffffff84f89fd3>] snd_rawmidi_write+0x543/0xb30 sound/core/rawmidi.c:1273 >> >> [<ffffffff817b0323>] __vfs_write+0x113/0x480 fs/read_write.c:528 >> >> [<ffffffff817b1db7>] vfs_write+0x167/0x4a0 fs/read_write.c:577 >> >> [< inline >] SYSC_write fs/read_write.c:624 >> >> [<ffffffff817b50a1>] SyS_write+0x111/0x220 fs/read_write.c:616 >> >> [<ffffffff86336c36>] entry_SYSCALL_64_fastpath+0x16/0x7a >> >> arch/x86/entry/entry_64.S:185 >> >> ---[ end trace 93509ba74cc3e259 ]--- >> >> >> >> >> >> // autogenerated by syzkaller (http://github.com/google/syzkaller) >> >> #include <pthread.h> >> >> #include <stdint.h> >> >> #include <string.h> >> >> #include <sys/syscall.h> >> >> #include <unistd.h> >> >> #include <fcntl.h> >> >> >> >> long r[11]; >> >> >> >> void* thr(void* arg) >> >> { >> >> switch ((long)arg) { >> >> case 0: >> >> r[0] = syscall(SYS_mmap, 0x20000000ul, 0x10000ul, 0x3ul, 0x32ul, >> >> 0xfffffffffffffffful, 0x0ul); >> >> break; >> >> case 1: >> >> r[1] = syscall(SYS_open, "/dev/dmmidi2", O_RDWR, 0); >> >> break; >> >> case 2: >> >> *(uint32_t*)0x20006fda = (uint32_t)0x28; >> >> *(uint32_t*)0x20006fde = (uint32_t)0x7; >> >> *(uint64_t*)0x20006fe2 = (uint64_t)0x0; >> >> *(uint64_t*)0x20006fea = (uint64_t)0x7; >> >> *(uint64_t*)0x20006ff2 = (uint64_t)0x8; >> >> *(uint16_t*)0x20006ffa = (uint16_t)0xfffffffffffffff8; >> >> r[8] = syscall(SYS_write, r[1], 0x20006fdaul, 0x28ul, 0, 0, 0); >> >> break; >> >> case 3: >> >> memcpy((void*)0x20007000, >> >> "\x3c\x3f\xbc\xd7\x07\xee\x01\x21\x84\x26\x11\x6d\xc6\xc3" >> >> "\xac\x7f\x14\xa3\x15\xda\xa1\x34\x67\xe9\xb6\xf8\xa8\xdd" >> >> "\xb5\xe0\x2a\x64\x6e\x04\x7c\x40\xdb\x64\x4f\x53\x41\x90" >> >> "\x02\x3b\x48\xba\xf6\xd7\x32\xe5\x11\x3f\xe5\xc5\xf2\x5f" >> >> "\x4e\x6f\x5b\xe9\x0e\x76\x1a\x72\x77\x68\xad\xd3\x1b\x8d" >> >> "\x8f\x71\x2f\x40\xde\xf4\xbf\x78\x48\xc2\xc3\xe5\xe9\x11" >> >> "\x11\xd2\x9a\x91\x94\x81\x57\x22\xef\x2a\x5b\xe2\x9e\xce" >> >> "\x3f\xa6\x07\x54\xd4\xb6\x1f\x30\xfd\x09\x35\x54\xcc\x78" >> >> "\x12\x37\x59\xf7\x5c\x51\xd2\x47\xb8\x40\x98\x2b\xb4\x8d" >> >> "\xbf\xd5\x34\x26\xcd\xb5\xe4\x98\x2d\x0e\xb1\x71\x0f\x12" >> >> "\x06\xb0\x2c\x78\x74\xba\x3d\x32\x9c\x72\x96\x0d\x91\x50" >> >> "\x9a\xe3\xbc\x4f\x1e\x26\xb2\xe3\xb2\xa2\x68\x6f\x10\xb5" >> >> "\xc1\x7f\xfc\xfd\xf0\xe6\xd9\x0c\xa0\xa7\x54\x2c\x62\x0d" >> >> "\xee\x04\x5b\x9d\x73\xf4\xcc\x29\x37\x01\xc2\x35\x8d\x3c" >> >> "\x8a\x2f\xe3\xf5\x55\x42\x77\x55\x2d\x49\x6f\x46\xf7\x34" >> >> "\xb1\x5f\xe7\x98\x55\xb5\x7c\x4e\xd7\x47\x18\xd1\xf9\xf2" >> >> "\xd2\xfe\x47\xff\x22\x04\xa9\x32\xe9\xd6\x28\xda\xe1\x85" >> >> "\xcb\xc5\xe6\xc1\xca\x9e\x3f\x1f\x80\xe6", >> >> 248); >> >> r[10] = syscall(SYS_write, r[1], 0x20007000ul, 0xf8ul, 0, 0, 0); >> >> break; >> >> } >> >> return 0; >> >> } >> >> >> >> int main() >> >> { >> >> long i; >> >> pthread_t th[4]; >> >> >> >> memset(r, -1, sizeof(r)); >> >> for (i = 0; i < 4; i++) { >> >> pthread_create(&th[i], 0, thr, (void*)i); >> >> usleep(10000); >> >> } >> >> for (i = 0; i < 4; i++) { >> >> pthread_create(&th[i], 0, thr, (void*)i); >> >> if (i % 2 == 0) >> >> usleep(10000); >> >> } >> >> usleep(100000); >> >> return 0; >> >> } >> >> >> >> On commit 30f05309bde49295e02e45c7e615f73aa4e0ccc2. >> > >> > Could you check the patch below? It's untested yet in my side due to >> > other bugs... >> >> No, I still see the same warning. >> Please try to reproduce it locally and test. > > This wasn't triggered on my machine. How did you start the test > program? I've attached my config. Then I start qemu as: $ qemu-system-x86_64 -hda /usr/local/google/home/dvyukov/bin/wheezy.img -net user,host=10.0.2.10,hostfwd=tcp::10022-:22 -net nic -nographic -kernel arch/x86/boot/bzImage -append "console=ttyS0 root=/dev/sda debug earlyprintk=serial slub_debug=UZ" -enable-kvm -pidfile vm_pid -m 2G -numa node,nodeid=0,cpus=0-1 -numa node,nodeid=1,cpus=2-3 -smp sockets=2,cores=2,threads=1 -usb -usbdevice mouse -usbdevice tablet -soundhw all Then I start programs using stress utility, if you have Go toolchain installed you can get it with: $ go get golang.org/x/tools/cmd/stress $ ./stress -p 32 -failure=foobar ./a.out This will run a.out constantly keeping 32 parallel processes and ignoring any failures a.out itself. > Meanwhile below is another patch to be applied in addition to the > previous fix. There is a possible race in calling > snd_rawmidi_transmit(), and this may result in such a warning. > > > Takashi > > --- > From: Takashi Iwai <tiwai@xxxxxxx> > Subject: [PATCH] ALSA: rawmidi: Make snd_rawmidi_transmit() race-free > > Signed-off-by: Takashi Iwai <tiwai@xxxxxxx> > --- > sound/core/rawmidi.c | 95 ++++++++++++++++++++++++++++++++++------------------ > 1 file changed, 62 insertions(+), 33 deletions(-) > > diff --git a/sound/core/rawmidi.c b/sound/core/rawmidi.c > index a7759846fbaa..3a27944c821c 100644 > --- a/sound/core/rawmidi.c > +++ b/sound/core/rawmidi.c > @@ -1054,24 +1054,9 @@ int snd_rawmidi_transmit_empty(struct snd_rawmidi_substream *substream) > } > EXPORT_SYMBOL(snd_rawmidi_transmit_empty); > > -/** > - * snd_rawmidi_transmit_peek - copy data from the internal buffer > - * @substream: the rawmidi substream > - * @buffer: the buffer pointer > - * @count: data size to transfer > - * > - * Copies data from the internal output buffer to the given buffer. > - * > - * Call this in the interrupt handler when the midi output is ready, > - * and call snd_rawmidi_transmit_ack() after the transmission is > - * finished. > - * > - * Return: The size of copied data, or a negative error code on failure. > - */ > -int snd_rawmidi_transmit_peek(struct snd_rawmidi_substream *substream, > +static int rawmidi_transmit_peek(struct snd_rawmidi_substream *substream, > unsigned char *buffer, int count) > { > - unsigned long flags; > int result, count1; > struct snd_rawmidi_runtime *runtime = substream->runtime; > > @@ -1081,7 +1066,6 @@ int snd_rawmidi_transmit_peek(struct snd_rawmidi_substream *substream, > return -EINVAL; > } > result = 0; > - spin_lock_irqsave(&runtime->lock, flags); > if (runtime->avail >= runtime->buffer_size) { > /* warning: lowlevel layer MUST trigger down the hardware */ > goto __skip; > @@ -1106,25 +1090,39 @@ int snd_rawmidi_transmit_peek(struct snd_rawmidi_substream *substream, > } > } > __skip: > - spin_unlock_irqrestore(&runtime->lock, flags); > return result; > } > -EXPORT_SYMBOL(snd_rawmidi_transmit_peek); > > /** > - * snd_rawmidi_transmit_ack - acknowledge the transmission > + * snd_rawmidi_transmit_peek - copy data from the internal buffer > * @substream: the rawmidi substream > - * @count: the transferred count > + * @buffer: the buffer pointer > + * @count: data size to transfer > * > - * Advances the hardware pointer for the internal output buffer with > - * the given size and updates the condition. > - * Call after the transmission is finished. > + * Copies data from the internal output buffer to the given buffer. > * > - * Return: The advanced size if successful, or a negative error code on failure. > + * Call this in the interrupt handler when the midi output is ready, > + * and call snd_rawmidi_transmit_ack() after the transmission is > + * finished. > + * > + * Return: The size of copied data, or a negative error code on failure. > */ > -int snd_rawmidi_transmit_ack(struct snd_rawmidi_substream *substream, int count) > +int snd_rawmidi_transmit_peek(struct snd_rawmidi_substream *substream, > + unsigned char *buffer, int count) > { > + struct snd_rawmidi_runtime *runtime = substream->runtime; > + int result; > unsigned long flags; > + > + spin_lock_irqsave(&runtime->lock, flags); > + result = rawmidi_transmit_peek(substream, buffer, count); > + spin_unlock_irqrestore(&runtime->lock, flags); > + return result; > +} > +EXPORT_SYMBOL(snd_rawmidi_transmit_peek); > + > +static int rawmidi_transmit_ack(struct snd_rawmidi_substream *substream, int count) > +{ > struct snd_rawmidi_runtime *runtime = substream->runtime; > > if (runtime->buffer == NULL) { > @@ -1132,7 +1130,6 @@ int snd_rawmidi_transmit_ack(struct snd_rawmidi_substream *substream, int count) > "snd_rawmidi_transmit_ack: output is not active!!!\n"); > return -EINVAL; > } > - spin_lock_irqsave(&runtime->lock, flags); > snd_BUG_ON(runtime->avail + count > runtime->buffer_size); > runtime->hw_ptr += count; > runtime->hw_ptr %= runtime->buffer_size; > @@ -1142,9 +1139,31 @@ int snd_rawmidi_transmit_ack(struct snd_rawmidi_substream *substream, int count) > if (runtime->drain || snd_rawmidi_ready(substream)) > wake_up(&runtime->sleep); > } > - spin_unlock_irqrestore(&runtime->lock, flags); > return count; > } > + > +/** > + * snd_rawmidi_transmit_ack - acknowledge the transmission > + * @substream: the rawmidi substream > + * @count: the transferred count > + * > + * Advances the hardware pointer for the internal output buffer with > + * the given size and updates the condition. > + * Call after the transmission is finished. > + * > + * Return: The advanced size if successful, or a negative error code on failure. > + */ > +int snd_rawmidi_transmit_ack(struct snd_rawmidi_substream *substream, int count) > +{ > + struct snd_rawmidi_runtime *runtime = substream->runtime; > + int result; > + unsigned long flags; > + > + spin_lock_irqsave(&runtime->lock, flags); > + result = rawmidi_transmit_ack(substream, count); > + spin_unlock_irqrestore(&runtime->lock, flags); > + return result; > +} > EXPORT_SYMBOL(snd_rawmidi_transmit_ack); > > /** > @@ -1160,12 +1179,22 @@ EXPORT_SYMBOL(snd_rawmidi_transmit_ack); > int snd_rawmidi_transmit(struct snd_rawmidi_substream *substream, > unsigned char *buffer, int count) > { > + struct snd_rawmidi_runtime *runtime = substream->runtime; > + int result; > + unsigned long flags; > + > + spin_lock_irqsave(&runtime->lock, flags); > if (!substream->opened) > - return -EBADFD; > - count = snd_rawmidi_transmit_peek(substream, buffer, count); > - if (count < 0) > - return count; > - return snd_rawmidi_transmit_ack(substream, count); > + result = -EBADFD; > + else { > + count = rawmidi_transmit_peek(substream, buffer, count); > + if (count <= 0) > + result = count; > + else > + result = rawmidi_transmit_ack(substream, count); > + } > + spin_unlock_irqrestore(&runtime->lock, flags); > + return result; > } > EXPORT_SYMBOL(snd_rawmidi_transmit); > > -- > 2.7.0 >
Attachment:
.config
Description: Binary data
_______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
