From 7a2c17fcbb789997421725d726340301ef35d84c Mon Sep 17 00:00:00 2001 From: James Clarke Date: Thu, 27 Aug 2015 17:22:11 +0100 Subject: Fix race condition in ext2fs when remounting On some systems, ext2fs.static would regularly hang at startup, as a race condition meant it would process paging requests while remounting. To fix this, libpager has been altered to allow inhibiting and resuming its worker threads, and ext2fs uses this to inhibit paging while remounting. * console/pager.c (pager_requests): New variable. (user_pager_init): Updated call to pager_start_workers to use new pager_requests variable. * daemons/runsystem.sh: Removed artificial delay working around the race condition. * ext2fs/ext2fs.c (diskfs_reload_global_state): Call new inhibit_ext2_pager and resume_ext2_pager functions, and leave sblock as non-NULL so it will be munmapped. * ext2fs/ext2fs.h (inhibit_ext2_pager,resume_ext2_pager): New functions. * ext2fs/pager.c (file_pager_requests): New variable. (create_disk_pager): Updated call to pager_start_workers to use new file_pager_requests variable. (inhibit_ext2_pager,resume_ext2_pager): New functions. * fatfs/fatfs.h (inhibit_fat_pager,resume_fat_pager): New functions. * fatfs/pager.c (file_pager_requests): New variable. (create_fat_pager): Updated call to pager_start_workers to use new file_pager_requests variable. (inhibit_fat_pager,resume_fat_pager): New functions. * libdiskfs/disk-pager.c (diskfs_disk_pager_requests): New variable. (diskfs_start_disk_pager): Updated call to pager_start_workers to use new diskfs_disk_pager_requests variable. * libdiskfs/diskfs-pager.h (diskfs_disk_pager_requests): New variable. * libpager/demuxer.c (struct pager_requests): Renamed struct requests to struct pager_requests. Replaced queue with queue_in and queue_out pointers. Added inhibit_wakeup field. (pager_demuxer): Updated to use new queue_in/queue_out pointers. Only wake up workers if not inhibited. (worker_func): Updated to use new queue_in/queue_out pointers. Final worker thread to sleep notifies the inhibit_wakeup condition variable. (pager_start_workers): Added out parameter for the requests instance. Allocate heap space shared by both queues. Initialise new inhibit_wakeup condition. (pager_inhibit_workers,pager_resume_workers): New functions. * libpager/pager.h (struct pager_requests): Public forward definition. (pager_start_workers): Added out parameter for the requests instance. (pager_inhibit_workers,pager_resume_workers): New functions. * libpager/queue.h (queue_empty): New function. * storeio/pager.c (pager_requests): New variable. (init_dev_paging): Updated call to pager_start_workers to use new pager_requests variable. --- console/pager.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'console') diff --git a/console/pager.c b/console/pager.c index 5e13ba48..818e49d7 100644 --- a/console/pager.c +++ b/console/pager.c @@ -42,6 +42,7 @@ struct user_pager_info /* We need a separate bucket for the pager ports. */ static struct port_bucket *pager_bucket; +static struct pager_requests *pager_requests; /* Implement the pager_clear_user_data callback from the pager library. */ @@ -133,7 +134,7 @@ user_pager_init (void) error (5, errno, "Cannot create pager bucket"); /* Start libpagers worker threads. */ - err = pager_start_workers (pager_bucket); + err = pager_start_workers (pager_bucket, &pager_requests); if (err) error (5, err, "Cannot start pager worker threads"); } -- cgit v1.2.3