Re: using long instead of atomic_t when only set/read is required (was Re: [Bug 10030] Suspend doesn't work when SD card is inserted) | KernelTrap

Re: using long instead of atomic_t when only set/read is required (was Re: [Bug 10030] Suspend doesn't work when SD card is inserted)

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From: Alan Stern <stern@...>

To: Pavel Machek <pavel@...>

Cc: Zdenek Kabelac <zdenek.kabelac@...>, <davem@...>, Rafael J. Wysocki <rjw@...>, Pierre Ossman <drzeus-mmc@...>, Kernel development list <linux-kernel@...>, pm list <linux-pm@...>

Subject: Re: using long instead of atomic_t when only set/read is required (was Re: [Bug 10030] Suspend doesn't work when SD card is inserted)

Date: Monday, February 25, 2008 - 10:46 am

On Mon, 25 Feb 2008, Pavel Machek wrote:

quoted text> Hi!
> 
> Alan thinks that `subj` is correct...

More precisely, reads and writes of pointers are always atomic.  That 
is, if a write and a read occur concurrently, it is guaranteed that the 
read will obtain either the old or the new value of the pointer, never 
a mish-mash of the two.  If this were not so then RCU wouldn't work.

quoted text> I guess it only works as long as longs are aligned? Should it be
> written down to atomic_ops.txt?

Forget it, I'm going to withdraw the entire thing.  The whole approach 
is wrong.  More details in a new email thread, to follow soon.

Alan Stern

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Messages in current thread:

Re: [Bug 10030] Suspend doesn't work when SD card is inserted, Alan Stern, (Wed Feb 20, 12:42 pm)

Re: [Bug 10030] Suspend doesn't work when SD card is inserted, Pierre Ossman, (Wed Feb 20, 1:30 pm)

Re: [Bug 10030] Suspend doesn't work when SD card is inserted, Alan Stern, (Wed Feb 20, 3:26 pm)

Re: [Bug 10030] Suspend doesn't work when SD card is inserted, Pierre Ossman, (Wed Feb 20, 4:51 pm)

Re: [Bug 10030] Suspend doesn't work when SD card is inserted, Alan Stern, (Wed Feb 20, 5:06 pm)

Re: [Bug 10030] Suspend doesn't work when SD card is inserted, Rafael J. Wysocki, (Wed Feb 20, 6:15 pm)

Re: [Bug 10030] Suspend doesn't work when SD card is inserted, Alan Stern, (Wed Feb 20, 6:24 pm)

Re: [Bug 10030] Suspend doesn't work when SD card is inserted, Rafael J. Wysocki, (Wed Feb 20, 8:02 pm)

Re: [Bug 10030] Suspend doesn't work when SD card is inserted, Alan Stern, (Thu Feb 21, 12:27 pm)

Re: [Bug 10030] Suspend doesn't work when SD card is inserted, Rafael J. Wysocki, (Thu Feb 21, 12:38 pm)

Re: [Bug 10030] Suspend doesn't work when SD card is inserted, Alan Stern, (Thu Feb 21, 1:48 pm)

Re: [Bug 10030] Suspend doesn't work when SD card is inserted, Rafael J. Wysocki, (Thu Feb 21, 6:47 pm)

Re: [Bug 10030] Suspend doesn't work when SD card is inserted, Alan Stern, (Thu Feb 21, 7:05 pm)

Re: [Bug 10030] Suspend doesn't work when SD card is inserted, Rafael J. Wysocki, (Fri Feb 22, 9:30 pm)

Re: [Bug 10030] Suspend doesn't work when SD card is inserted, Alan Stern, (Sat Feb 23, 12:39 am)

Re: [Bug 10030] Suspend doesn't work when SD card is inserted, Rafael J. Wysocki, (Sat Feb 23, 4:16 pm)

Re: [Bug 10030] Suspend doesn't work when SD card is inserted, Alan Stern, (Sat Feb 23, 7:29 pm)

Re: [Bug 10030] Suspend doesn't work when SD card is inserted, Rafael J. Wysocki, (Sat Feb 23, 8:19 pm)

Re: [Bug 10030] Suspend doesn't work when SD card is inserted, Alan Stern, (Sat Feb 23, 11:25 pm)

Re: [linux-pm] [Bug 10030] Suspend doesn't work when SD card..., Alan Stern, (Sun Feb 24, 12:26 am)

Re: [linux-pm] [Bug 10030] Suspend doesn't work when SD card..., Rafael J. Wysocki, (Sun Feb 24, 10:00 am)

Bugs in MMC [was: [Bug 10030] Suspend doesn't work when SD c..., Alan Stern, (Sun Feb 24, 11:33 am)

Re: Bugs in MMC [was: [Bug 10030] Suspend doesn't work when ..., Pierre Ossman, (Mon Feb 25, 1:41 pm)

Re: Bugs in MMC [was: [Bug 10030] Suspend doesn't work when ..., Alan Stern, (Mon Feb 25, 1:58 pm)

Re: Bugs in MMC [was: [Bug 10030] Suspend doesn't work when ..., Pierre Ossman, (Mon Feb 25, 2:31 pm)

Re: Bugs in MMC [was: [Bug 10030] Suspend doesn't work when ..., Alan Stern, (Mon Feb 25, 4:00 pm)

Re: Bugs in MMC [was: [Bug 10030] Suspend doesn't work when ..., Pierre Ossman, (Sat Mar 1, 10:11 am)

Re: Bugs in MMC [was: [Bug 10030] Suspend doesn't work when ..., Alan Stern, (Sat Mar 1, 10:36 am)

Re: Bugs in MMC [was: [Bug 10030] Suspend doesn't work when ..., Pierre Ossman, (Sat Mar 1, 10:47 am)

Re: Bugs in MMC [was: [Bug 10030] Suspend doesn't work when ..., Felipe Balbi, (Mon Feb 25, 6:51 pm)

Re: Bugs in MMC [was: [Bug 10030] Suspend doesn't work when ..., David Brownell, (Mon Mar 3, 5:59 pm)

Re: Bugs in MMC [was: [Bug 10030] Suspend doesn't work when ..., Alan Stern, (Tue Mar 4, 1:50 pm)

Re: Bugs in MMC [was: [Bug 10030] Suspend doesn't work when ..., Pierre Ossman, (Tue Mar 4, 2:03 am)

Re: Bugs in MMC [was: [Bug 10030] Suspend doesn't work when ..., David Brownell, (Tue Mar 4, 5:44 am)

Re: Bugs in MMC [was: [Bug 10030] Suspend doesn't work when ..., Alan Stern, (Tue Mar 4, 1:53 pm)

Re: Bugs in MMC [was: [Bug 10030] Suspend doesn't work when ..., David Brownell, (Tue Mar 4, 2:53 pm)

Re: Bugs in MMC [was: [Bug 10030] Suspend doesn't work when ..., Alan Stern, (Tue Mar 4, 3:51 pm)

Re: Bugs in MMC [was: [Bug 10030] Suspend doesn't work when ..., David Brownell, (Tue Mar 4, 4:30 pm)

Re: Bugs in MMC [was: [Bug 10030] Suspend doesn't work when ..., Alan Stern, (Tue Mar 4, 5:00 pm)

Re: Bugs in MMC [was: [Bug 10030] Suspend doesn't work when ..., Pavel Machek, (Thu Mar 6, 11:55 am)

Re: Bugs in MMC [was: [Bug 10030] Suspend doesn't work when ..., Alan Stern, (Thu Mar 6, 4:33 pm)

Re: Bugs in MMC [was: [Bug 10030] Suspend doesn't work when ..., Zdenek Kabelac, (Thu Mar 6, 4:53 pm)

Re: Bugs in MMC [was: [Bug 10030] Suspend doesn't work when ..., Rafael J. Wysocki, (Thu Mar 6, 5:31 pm)

Re: Bugs in MMC [was: [Bug 10030] Suspend doesn't work when ..., Pierre Ossman, (Tue Mar 4, 5:58 am)

Re: Bugs in MMC [was: [Bug 10030] Suspend doesn't work when ..., David Brownell, (Thu Mar 6, 5:23 pm)

Re: [Bug 10030] Suspend doesn't work when SD card is inserted, Pavel Machek, (Sun Feb 24, 2:21 pm)

Re: [Bug 10030] Suspend doesn't work when SD card is inserted, Alan Stern, (Sun Feb 24, 3:03 pm)

Re: [Bug 10030] Suspend doesn't work when SD card is inserted, Pavel Machek, (Sun Feb 24, 4:11 pm)

Re: [Bug 10030] Suspend doesn't work when SD card is inserted, Alan Stern, (Sun Feb 24, 4:33 pm)

Re: [Bug 10030] Suspend doesn't work when SD card is inserted, Pavel Machek, (Sun Feb 24, 5:42 pm)

Re: [Bug 10030] Suspend doesn't work when SD card is inserted, Alan Stern, (Sun Feb 24, 10:19 pm)

Re: [Bug 10030] Suspend doesn't work when SD card is inserted, Rafael J. Wysocki, (Mon Feb 25, 7:40 am)

using long instead of atomic_t when only set/read is require..., Pavel Machek, (Mon Feb 25, 5:03 am)

Re: using long instead of atomic_t when only set/read is req..., Alan Stern, (Mon Feb 25, 10:46 am)

[patch] Re: using long instead of atomic_t when only set/rea..., Pavel Machek, (Mon Mar 3, 8:08 am)

Re: [patch] Re: using long instead of atomic_t when only set..., Alan Stern, (Mon Mar 3, 11:42 am)

Re: [patch] Re: using long instead of atomic_t when only set..., Paul E. McKenney, (Mon Mar 3, 1:22 pm)

Re: [patch] Re: using long instead of atomic_t when only set..., Alan Cox, (Mon Mar 3, 11:53 am)

Re: [patch] Re: using long instead of atomic_t when only set..., Alan Stern, (Mon Mar 3, 1:11 pm)

Re: [patch] Re: using long instead of atomic_t when only set..., Linus Torvalds, (Mon Mar 3, 1:26 pm)

Re: [patch] Re: using long instead of atomic_t when only set..., Mark Lord, (Thu Mar 6, 11:58 am)

Re: [patch] Re: using long instead of atomic_t when only set..., Linus Torvalds, (Thu Mar 6, 12:11 pm)

Re: [patch] Re: using long instead of atomic_t when only set..., Mark Lord, (Thu Mar 6, 12:27 pm)

Re: [patch] Re: using long instead of atomic_t when only set..., Pavel Machek, (Mon Mar 3, 1:44 pm)

Re: [patch] Re: using long instead of atomic_t when only set..., Alan Stern, (Mon Mar 3, 3:27 pm)

Re: [patch] Re: using long instead of atomic_t when only set..., Nick Piggin, (Mon Mar 3, 1:16 pm)

Re: [patch] Re: using long instead of atomic_t when only set..., Alan Cox, (Mon Mar 3, 1:33 pm)

Re: [patch] Re: using long instead of atomic_t when only set..., Paul E. McKenney, (Mon Mar 3, 1:31 pm)

Re: [patch] Re: using long instead of atomic_t when only set..., Alan Cox, (Mon Mar 3, 11:48 am)

Re: [patch] Re: using long instead of atomic_t when only set..., Pavel Machek, (Mon Mar 3, 1:24 pm)

Re: [patch] Re: using long instead of atomic_t when only set..., Rafael J. Wysocki, (Mon Mar 3, 4:27 pm)

Re: [patch] Re: using long instead of atomic_t when only set..., Linus Torvalds, (Mon Mar 3, 6:23 pm)

Re: [patch] Re: using long instead of atomic_t when only set..., Paul E. McKenney, (Mon Mar 3, 5:12 pm)

Re: [patch] Re: using long instead of atomic_t when only set..., Peter Hartley, (Tue Mar 4, 7:32 pm)

Re: [patch] Re: using long instead of atomic_t when only set..., Rafael J. Wysocki, (Tue Mar 4, 7:54 pm)

Re: [patch] Re: using long instead of atomic_t when only set..., Paul E. McKenney, (Tue Mar 4, 8:26 pm)

Re: [Bug 10030] Suspend doesn't work when SD card is inserted, Rafael J. Wysocki, (Sun Feb 24, 6:21 pm)

Re: [Bug 10030] Suspend doesn't work when SD card is inserted, Alan Stern, (Sun Feb 24, 10:21 pm)

Re: [Bug 10030] Suspend doesn't work when SD card is inserted, Rafael J. Wysocki, (Mon Feb 25, 7:41 am)

Re: [Bug 10030] Suspend doesn't work when SD card is inserted, Rafael J. Wysocki, (Sun Feb 24, 9:51 am)

Re: [Bug 10030] Suspend doesn't work when SD card is inserted, Alan Stern, (Sun Feb 24, 3:27 pm)

Re: [Bug 10030] Suspend doesn't work when SD card is inserted, Zdenek Kabelac, (Sun Feb 24, 3:42 pm)

Re: [Bug 10030] Suspend doesn't work when SD card is inserted, Rafael J. Wysocki, (Sun Feb 24, 4:09 pm)

Re: [Bug 10030] Suspend doesn't work when SD card is inserted, Rafael J. Wysocki, (Sun Feb 24, 9:33 am)

Re: [Bug 10030] Suspend doesn't work when SD card is inserted, Rafael J. Wysocki, (Sun Feb 24, 4:25 pm)

Re: [Bug 10030] Suspend doesn't work when SD card is inserted, Alan Stern, (Sun Feb 24, 4:45 pm)

Re: [Bug 10030] Suspend doesn't work when SD card is inserted, Rafael J. Wysocki, (Sun Feb 24, 4:56 pm)

Re: [Bug 10030] Suspend doesn't work when SD card is inserted, Alan Stern, (Sun Feb 24, 5:11 pm)

Re: [Bug 10030] Suspend doesn't work when SD card is inserted, Rafael J. Wysocki, (Sun Feb 24, 6:18 pm)

Re: [Bug 10030] Suspend doesn't work when SD card is inserted, Rafael J. Wysocki, (Wed Feb 20, 6:41 pm)

Re: [Bug 10030] Suspend doesn't work when SD card is inserted, Rafael J. Wysocki, (Wed Feb 20, 4:58 pm)

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