From: Pedro Alves <palves@redhat.com>
To: Evgeniy Didin <Evgeniy.Didin@synopsys.com>, gdb-patches@sourceware.org
Cc: Cupertino Miranda <Cupertino.Miranda@synopsys.com>,
Vineet Gupta <Vineet.Gupta1@synopsys.com>,
Alexey Brodkin <Alexey.Brodkin@synopsys.com>,
Shahab Vahedi <Shahab.Vahedi@synopsys.com>,
linux-snps-arc@lists.infradead.org,
Claudiu Zissulescu <Claudiu.Zissulescu@synopsys.com>
Subject: Re: [PATCH v2] gdb/remote: Remove negative tid/pid handling in wite_ptid
Date: Wed, 6 Nov 2019 14:27:21 +0000 [thread overview]
Message-ID: <73f36a2f-444c-3057-f642-f9f7279574b5@redhat.com> (raw)
In-Reply-To: <20191106132732.11034-1-didin@synopsys.com>
On 11/6/19 1:27 PM, Evgeniy Didin wrote:
> Actually thread and process ID's are positive values. Accorting to
> http://man7.org/linux/man-pages/man7/pthreads.7.html
> threads are creating using "clone" syscall, so the ID generation mechanism
> is similar for threads and processes. According to Linux source code
> there is a function call tree, which allocates PID[TID]:
> clone
> |->_do_fork
> |->copy_process
> |->alloc_pid
> |->idr_alloc_cyclic
> |->idr_alloc_u32(idr, ptr, &id, max, gfp);
> And in idr_alloc_u32() "id" is u32 value, which means positiveness.
> Also according to:
> https://elixir.bootlin.com/linux/latest/source/kernel/pid.c#L177
> PID cannot be less than 1.
Sure for Linux. But negative numbers have meaning in the remote protocol:
https://sourceware.org/gdb/current/onlinedocs/gdb/Packets.html#thread_002did-syntax
Thanks,
Pedro Alves
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prev parent reply other threads:[~2019-11-06 14:27 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-06 13:27 [PATCH v2] gdb/remote: Remove negative tid/pid handling in wite_ptid Evgeniy Didin
2019-11-06 14:27 ` Pedro Alves [this message]
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