Messages in this thread | | | Subject | Re: [PATCH] atm: firestream: Replace GFP_ATOMIC with GFP_KERNEL in fs_send | From | Jia-Ju Bai <> | Date | Fri, 26 Jan 2018 22:17:08 +0800 |
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On 2018/1/26 21:56, Jia-Ju Bai wrote: > > > On 2018/1/26 20:05, Al Viro wrote: >> 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... > > Thanks for reply :) > > I am sorry for this false positive. > I think other ATM related patches that I submitted are also false > positives, sorry. > My tool did not handle this situation of passing function pointer, and > I will improve the tool... > > > Thanks, > Jia-Ju Bai
I check the code again, and confirm only my patches about "send" are false positives. I think other my patches that are about "open" does not has this problem: https://marc.info/?l=linux-kernel&m=151693791432626&w=2 https://marc.info/?l=linux-kernel&m=151695475503314&w=2 https://marc.info/?l=linux-kernel&m=151693150131512&w=2
I hope you can have a check :)
Thanks, Jia-Ju Bai
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