/* CacheFiles statistics * * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved. * Written by David Howells (dhowells@redhat.com) * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public Licence * as published by the Free Software Foundation; either version * 2 of the Licence, or (at your option) any later version. */ #include #include #include #include "internal.h" atomic_t cachefiles_lookup_histogram[HZ]; atomic_t cachefiles_mkdir_histogram[HZ]; atomic_t cachefiles_create_histogram[HZ]; /* * display the latency histogram */ static int cachefiles_histogram_show(struct seq_file *m, void *v) { unsigned long index; unsigned x, y, z, t; switch ((unsigned long) v) { case 1: seq_puts(m, "JIFS SECS LOOKUPS MKDIRS CREATES\n"); return 0; case 2: seq_puts(m, "===== ===== ========= ========= =========\n"); return 0; default: index = (unsigned long) v - 3; x = atomic_read(&cachefiles_lookup_histogram[index]); y = atomic_read(&cachefiles_mkdir_histogram[index]); z = atomic_read(&cachefiles_create_histogram[index]); if (x == 0 && y == 0 && z == 0) return 0; t = (index * 1000) / HZ; seq_printf(m, "%4lu 0.%03u %9u %9u %9u\n", index, t, x, y, z); return 0; } } /* * set up the iterator to start reading from the first line */ static void *cachefiles_histogram_start(struct seq_file *m, loff_t *_pos) { if ((unsigned long long)*_pos >= HZ + 2) return NULL; if (*_pos == 0) *_pos = 1; return (void *)(unsigned long) *_pos; } /* * move to the next line */ static void *cachefiles_histogram_next(struct seq_file *m, void *v, loff_t *pos) { (*pos)++; return (unsigned long long)*pos > HZ + 2 ? NULL : (void *)(unsigned long) *pos; } /* * clean up after reading */ static void cachefiles_histogram_stop(struct seq_file *m, void *v) { } static const struct seq_operations cachefiles_histogram_ops = { .start = cachefiles_histogram_start, .stop = cachefiles_histogram_stop, .next = cachefiles_histogram_next, .show = cachefiles_histogram_show, }; /* * open "/proc/fs/cachefiles/XXX" which provide statistics summaries */ static int cachefiles_histogram_open(struct inode *inode, struct file *file) { return seq_open(file, &cachefiles_histogram_ops); } static const struct file_operations cachefiles_histogram_fops = { .open = cachefiles_histogram_open, .read = seq_read, .llseek = seq_lseek, .release = seq_release, }; /* * initialise the /proc/fs/cachefiles/ directory */ int __init cachefiles_proc_init(void) { _enter(""); if (!proc_mkdir("fs/cachefiles", NULL)) goto error_dir; if (!proc_create("fs/cachefiles/histogram", S_IFREG | 0444, NULL, &cachefiles_histogram_fops)) goto error_histogram; _leave(" = 0"); return 0; error_histogram: remove_proc_entry("fs/cachefiles", NULL); error_dir: _leave(" = -ENOMEM"); return -ENOMEM; } /* * clean up the /proc/fs/cachefiles/ directory */ void cachefiles_proc_cleanup(void) { remove_proc_entry("fs/cachefiles/histogram", NULL); remove_proc_entry("fs/cachefiles", NULL); } alue='91539eb1fda2d530d3b268eef542c5414e54bf1a'/>
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authorIago Abal <mail@iagoabal.eu>2017-01-11 14:00:21 +0100
committerVinod Koul <vinod.koul@intel.com>2017-01-25 15:35:11 +0530
commit91539eb1fda2d530d3b268eef542c5414e54bf1a (patch)
tree960f5ca6342ad20837aff18aad6e8ecd7da32fd6 /fs/nfsd/nfsd.h
parent6610d0edf6dc7ee97e46ab3a538a565c79d26199 (diff)
dmaengine: pl330: fix double lock
The static bug finder EBA (http://www.iagoabal.eu/eba/) reported the following double-lock bug: Double lock: 1. spin_lock_irqsave(pch->lock, flags) at pl330_free_chan_resources:2236; 2. call to function `pl330_release_channel' immediately after; 3. call to function `dma_pl330_rqcb' in line 1753; 4. spin_lock_irqsave(pch->lock, flags) at dma_pl330_rqcb:1505. I have fixed it as suggested by Marek Szyprowski. First, I have replaced `pch->lock' with `pl330->lock' in functions `pl330_alloc_chan_resources' and `pl330_free_chan_resources'. This avoids the double-lock by acquiring a different lock than `dma_pl330_rqcb'. NOTE that, as a result, `pl330_free_chan_resources' executes `list_splice_tail_init' on `pch->work_list' under lock `pl330->lock', whereas in the rest of the code `pch->work_list' is protected by `pch->lock'. I don't know if this may cause race conditions. Similarly `pch->cyclic' is written by `pl330_alloc_chan_resources' under `pl330->lock' but read by `pl330_tx_submit' under `pch->lock'. Second, I have removed locking from `pl330_request_channel' and `pl330_release_channel' functions. Function `pl330_request_channel' is only called from `pl330_alloc_chan_resources', so the lock is already held. Function `pl330_release_channel' is called from `pl330_free_chan_resources', which already holds the lock, and from `pl330_del'. Function `pl330_del' is called in an error path of `pl330_probe' and at the end of `pl330_remove', but I assume that there cannot be concurrent accesses to the protected data at those points. Signed-off-by: Iago Abal <mail@iagoabal.eu> Reviewed-by: Marek Szyprowski <m.szyprowski@samsung.com> Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Diffstat (limited to 'fs/nfsd/nfsd.h')