actually i dont see why there is a need to ptovide a lock by the kernel.
the locking should be at userspace.
you can test it by massive write to a file, that would demonstrat the kernel
didnt confer a lock
Hello,
I was looking at how a syscall read/write was done, and i found this :
....
loff_t pos = file_pos_read(f.file);
ret = vfs_read(f.file, buf, count, &pos);
file_pos_write(f.file, pos);
fdput(f);
...
My questions are :
Where did the locking go? I would have imaginated something like :
....
lock(f);
loff_t pos = file_pos_read(f.file);
ret = vfs_read(f.file, buf, count, &pos);
file_pos_write(f.file, pos);
fdput(f);
unlock(f);
...
If multiple threads try to read/write at the same time, they could read/write at the same offset ?
If my understanding are correct, is this POSIX compliant ?
thanks.
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