Opposition to software patents is widespread in the free software community. In response, various mechanisms have been tried to defuse the perceived problem. Positions from the community Community leaders such as Richard Stallman, Alan Cox, Bruce Perens, and Linus Torvalds and companies such as Red Hat, and MySQL, and community groups such as FSFE, IFSO, all believe that patents cause problems for free software. Patent licensing Leading open-source figures and companies have complained that software patents are overly broad and the USPTO should reject most of them. Bill Gates has said "If people had understood how patents would be granted when most of today’s ideas were invented, and had taken out patents, the industry would be at a complete standstill today". Problems for free software Free software projects cannot agree to patent licences that include any kind of per-copy fee. No matter how low the fee is, there is no way for a free software distributor to know how many copies are being made. Also, adding any requirements to pay or to notify someone each time a copy is made would make the software no longer free software. A patent licence that is royalty-free, or provides a one-time worldwide payment is acceptable. Version 2 of the GNU General Public License does not allow software to be distributed if that software requires a patent licence that does not "permit royalty-free redistribution of the Program by all those who receive copies directly or indirectly through you". The Version 2 of the GNU General Public License of 1991 also says that patents convert free software to proprietary software: "Finally, any free program is threatened constantly by software patents. We wish to avoid the danger that redistributors of a free program will individually obtain patent licenses, in effect making the program proprietary. To prevent this, we have made it clear that any patent must be licensed for everyone's free use or not licensed at all." The 2004 OSRM study In 2004, Open Source Risk Management commissioned a patent study, carried out by Dan Ravicher. For this study, Ravicher performed patent searches to estimate the patent-risk of the Linux kernel: In conclusion, he found that no court-validated software patent is infringed by the Linux kernel. However, Ravicher also found 283 issued but not yet court-validated software patents that, if upheld as valid by the courts, could potentially be used to support patent claims against Linux.However,