Messages in this thread | | | Subject | Re: [PATCH] atm: firestream: Replace GFP_ATOMIC with GFP_KERNEL in fs_send | From | Jia-Ju Bai <> | Date | Sat, 27 Jan 2018 00:17:53 +0800 |
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On 2018/1/27 0:07, David Miller wrote: > From: Al Viro <viro@ZenIV.linux.org.uk> > Date: Fri, 26 Jan 2018 12:05:22 +0000 > >> On Fri, Jan 26, 2018 at 04:00:27PM +0800, Jia-Ju Bai wrote: >>> After checking all possible call chains to fs_send() here, >>> my tool finds that fs_send() is never called in atomic context. >>> And this function is assigned to a function pointer "dev->ops->send", >>> which is only called by vcc_sendmsg() (net/atm/common.c) >>> through vcc->dev->ops->send(), and vcc_sendmsg() calls schedule(), >>> it indicates that fs_send() can call functions which may sleep. >>> Thus GFP_ATOMIC is not necessary, and it can be replaced with GFP_KERNEL. >>> >>> This is found by a static analysis tool named DCNS written by myself. >> The trouble is, places like >> net/atm/raw.c:65: vcc->send = atm_send_aal0; >> net/atm/raw.c:74: vcc->send = vcc->dev->ops->send; >> net/atm/raw.c:83: vcc->send = vcc->dev->ops->send; >> mean extra call chains. It's *not* just vcc_sendmsg(), and e.g. >> ret = ATM_SKB(skb)->vcc->send(ATM_SKB(skb)->vcc, skb) >> ? DROP_PACKET : 1; >> bh_unlock_sock(sk_atm(vcc)); >> in pppoatm_send() definitely is called under a spinlock. >> >> Looking through the driver (in advanced bitrot, as usual for drivers/atm), >> I'd say that submit_queue() is fucked in head in the "queue full" case. >> And judging by the history, had been thus since the original merge... > Jia-Ju, I'm probably not going to apply any of your GFP_KERNEL > conversions. > > Al's analysis above is similar to how things looked for other patches > you submited of this nature. > > So because of the lack of care and serious auditing you put into these > conversions, I really have no choice but to drop them from my queue > because on the whole they are adding bugs rather than improving the > code. > > Thank you.
Okay, I can understand that careless GFP_KERNEL conversions will introduce bugs. Your concern is right. Sorry for my previous incorrect patches... I will manually carefully check and audit my patches before I submit them.
Thanks, Jia-Ju Bai
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