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[Bug 1001591] New: Bogus pseudo-randomness in garbage collect
- From: bugzilla-daemon at bugs dot ecos dot sourceware dot org
- To: unassigned at bugs dot ecos dot sourceware dot org
- Date: Mon, 21 May 2012 14:02:17 +0100
- Subject: [Bug 1001591] New: Bogus pseudo-randomness in garbage collect
- Auto-submitted: auto-generated
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Summary: Bogus pseudo-randomness in garbage collect
Product: eCos
Version: CVS
Platform: All
OS/Version: All
Status: UNCONFIRMED
Severity: major
Priority: low
Component: Filesystem support
AssignedTo: unassigned@bugs.ecos.sourceware.org
ReportedBy: stano@meduna.org
CC: ecos-bugs@ecos.sourceware.org
Class: Advice Request
The jffs2_find_gc_block function in fs/jffs2/current/src/gc.c and
jffs2_mark_node_obsolete in nodemgmt.c try to do pseudo-random stuff by
computing jiffies % 128 and making probability decisions on the result. First I
think that this kind of pseudo-randomness is not really correct for embedded
systems that often have very predictable execution times.
But what is much worse, compat/linux/current/include/linux/kernel.h defines
jiffies as
#define jiffies 100
I am no expert at jffs2 and cannot say whether this can lead to major problems
or not, so I'd like someone with better understanding of jffs2 to look at it.
Also check other usage of jiffies - I found one more in
io/usb/eth/slave/current/host/ecos_usbeth.c
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