Re: [fuse-devel] poll() in CUSE behaves strangely

[Miklos S. <mi...@sz...>]

Miklos Szeredi <mi...@sz...> writes:

> Hans-Kristian Arntzen <ma...@ar...> writes:
>
>> I assume this is the correct mailing list for CUSE related posts.
>
> CUSE and OSSP are maintained by Tejun Heo.  I added him to the CC.
>
>> I've tried to implement a character device emulating OSS, but poll()
>> behaves strangely. It always returns immediately no matter the
>> timeout, and .revents is set equal to .events for some reason.
>>
>> The exact same behavior is found in ossp-padsp as well, so I believe
>> it's a bug in CUSE.
>> Kernel is Linux 3.0 - x86_64, fuse 2.8.5
>
> Can you get a debug log from OSSP as well?

Oops, sorry.  I see now that you already replied, that it was a user
error...

Thanks,
Miklos

>
> Thanks,
> Miklos
>
>>
>> Test program and result log is included. I wonder what could cause this.
>> Thanks in advance.
>>
>>
>>
>>
>>
>> #include <sys/soundcard.h>
>> #include <stdio.h>
>> #include <unistd.h>
>> #include <assert.h>
>> #include <fcntl.h>
>> #include <stdint.h>
>> #include <sys/ioctl.h>
>> #include <sys/poll.h>
>>
>> int main(int argc, char *argv[])
>> {
>>    assert(argc == 2);
>>    int fd = open(argv[1], O_WRONLY);
>>    assert(fd >= 0);
>>
>>    int param = 44100;
>>    int rc = ioctl(fd, SNDCTL_DSP_SPEED, &param);
>>    fprintf(stderr, "SPEED: rc = %d, param = %d\n",
>>          rc, param);
>>
>>    param = 2;
>>    rc = ioctl(fd, SNDCTL_DSP_CHANNELS, &param);
>>    fprintf(stderr, "CHANNELS: rc = %d, param = %d\n",
>>          rc, param);
>>
>>    param = AFMT_S16_LE;
>>    rc = ioctl(fd, SNDCTL_DSP_SETFMT, &param);
>>    fprintf(stderr, "FMT: rc = %d\n", rc);
>>
>>    audio_buf_info info;
>>    ioctl(fd, SNDCTL_DSP_GETOSPACE, &info);
>>    fprintf(stderr, "GETOSPACE: rc = %d, bytes = %d, fragments = %d, fragsize = %d, fragstotal = %d\n",
>>          rc, info.bytes, info.fragments, info.fragsize, info.fragstotal);
>>
>>    assert(fcntl(fd, F_SETFL, fcntl(fd, F_GETFL) | O_NONBLOCK) == 0);
>>
>>    uint8_t buf[1024];
>>    unsigned cnt = 0;
>>
>>    for (;;)
>>    {
>>       struct pollfd pfd = {
>>          .events = POLLOUT | POLLIN, // POLLIN for shits 'n giggles.
>>       };
>>
>>       if (poll(&pfd, 1, 1000) < 0)
>>          break;
>>
>>       fprintf(stderr, "poll(): POLLOUT = %d, .events = %u, .revents = %u, Count = %u\n",
>>             (pfd.revents & POLLOUT) ? 1 : 0,
>>             pfd.events,
>>             pfd.revents,
>>             cnt++);
>>
>>       if ((~pfd.revents) & POLLOUT)
>>          continue;
>>
>>       audio_buf_info info;
>>       ioctl(fd, SNDCTL_DSP_GETOSPACE, &info);
>>       size_t avail = sizeof(buf) < (size_t)info.bytes ? sizeof(buf) : (size_t)info.bytes;
>>       fprintf(stderr, "OSS write avail: %u\n", (unsigned)info.bytes);
>>
>>       if (read(0, buf, avail) <= 0)
>>          break;
>>
>>       if (write(fd, buf, avail) < 0)
>>          break;
>>    }
>>
>>    close(fd);
>> }
>>
>> SPEED: rc = 0, param = 44100
>> CHANNELS: rc = 0, param = 2
>> FMT: rc = 0
>> GETOSPACE: rc = 0, bytes = 65536, fragments = 4, fragsize = 16384, fragstotal = 4
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 0
>> OSS write avail: 65536
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 1
>> OSS write avail: 49152
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 2
>> OSS write avail: 49152
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 3
>> OSS write avail: 49152
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 4
>> OSS write avail: 49152
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 5
>> OSS write avail: 49152
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 6
>> OSS write avail: 49152
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 7
>> OSS write avail: 49152
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 8
>> OSS write avail: 49152
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 9
>> OSS write avail: 49152
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 10
>> OSS write avail: 49152
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 11
>> OSS write avail: 49152
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 12
>> OSS write avail: 49152
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 13
>> OSS write avail: 49152
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 14
>> OSS write avail: 49152
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 15
>> OSS write avail: 49152
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 16
>> OSS write avail: 49152
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 17
>> OSS write avail: 32768
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 18
>> OSS write avail: 32768
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 19
>> OSS write avail: 32768
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 20
>> OSS write avail: 32768
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 21
>> OSS write avail: 32768
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 22
>> OSS write avail: 32768
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 23
>> OSS write avail: 32768
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 24
>> OSS write avail: 32768
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 25
>> OSS write avail: 32768
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 26
>> OSS write avail: 32768
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 27
>> OSS write avail: 32768
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 28
>> OSS write avail: 32768
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 29
>> OSS write avail: 32768
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 30
>> OSS write avail: 32768
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 31
>> OSS write avail: 32768
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 32
>> OSS write avail: 32768
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 33
>> OSS write avail: 16384
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 34
>> OSS write avail: 16384
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 35
>> OSS write avail: 32768
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 36
>> OSS write avail: 32768
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 37
>> OSS write avail: 32768
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 38
>> OSS write avail: 32768
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 39
>> OSS write avail: 32768
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 40
>> OSS write avail: 32768
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 41
>> OSS write avail: 32768
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 42
>> OSS write avail: 32768
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 43
>> OSS write avail: 32768
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 44
>> OSS write avail: 32768
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 45
>> OSS write avail: 32768
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 46
>> OSS write avail: 32768
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 47
>> OSS write avail: 32768
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 48
>> OSS write avail: 32768
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 49
>> OSS write avail: 32768
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 50
>> OSS write avail: 16384
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 51
>> OSS write avail: 16384
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 52
>> OSS write avail: 16384
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 53
>> OSS write avail: 16384
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 54
>> OSS write avail: 16384
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 55
>> OSS write avail: 16384
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 56
>> OSS write avail: 16384
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 57
>> OSS write avail: 16384
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 58
>> OSS write avail: 16384
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 59
>> OSS write avail: 16384
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 60
>> OSS write avail: 16384
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 61
>> OSS write avail: 16384
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 62
>> OSS write avail: 16384
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 63
>> OSS write avail: 16384
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 64
>> OSS write avail: 16384
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 65
>> OSS write avail: 16384
>> poll(): POLLOUT = 1, .events = 5, .revents = 5, Count = 66
>> OSS write avail: 0
>> ------------------------------------------------------------------------------
>> Magic Quadrant for Content-Aware Data Loss Prevention
>> Research study explores the data loss prevention market. Includes in-depth
>> analysis on the changes within the DLP market, and the criteria used to
>> evaluate the strengths and weaknesses of these DLP solutions.
>> http://www.accelacomm.com/jaw/sfnl/114/51385063/_______________________________________________
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