pussuw opened a new pull request, #16361: URL: https://github.com/apache/nuttx/pull/16361
## Summary This PR is a rework of the NuttX file descriptor implementation. The goal is two-fold: 1. Improve POSIX compliance. The old implementation tied file description to inode only, not the file struct. POSIX however dictates otherwise. 2. Fix a bug with descriptor duplication (dup2() and dup3()). There is an existing race condition with this POSIX API that currently results in a kernel side crash. The crash occurs when a partially open / closed file descriptor is duplicated. The reason for the crash is that even if the descriptor is closed, the file might still be in use by the kernel (due to e.g. ongoing write to file). The open file data is changed by file_dup3() and this causes a crash in the device / drivers themselves as they lose access to the inode and private data. The fix is done by separating struct file into file and file descriptor structs. The file struct can live on even if the descriptor is closed, fixing the crash. This also fixes the POSIX issue, as two descriptors can now point to the same file. ## Impact The impact is big, this is basically a re-write of the file descriptor subsystem, so the possibility of regression is big. This change also removes the option for CONFIG_FS_REFCOUNT, since it is not possible to implement the new descriptor logic without the reference counter. User: The impact to user is opaque, with the exception of the removed CONFIG_FS_REFCOUNT option. Documentation: Documentation impact is not clear, depends on the level of documentation for the old vfs implementation Security: none Build system: none ## Testing Tested on MPFS target with KERNEL_BUILD=y, SMP=y and 100+ threads rv-virt:nsh64 ostest rv-virt:knsh64 ostest rv-virt:smp64 ostest rv-virt:ksmp64 ostest The motivation for this change can be found here: https://github.com/apache/nuttx/pull/16326 There are also open questions about some calls to e.g. file_dup2, it was not clear to me how to handle these. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: commits-unsubscr...@nuttx.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
